From 95fd56823152aaaadf3987145f950fd08527fe2f Mon Sep 17 00:00:00 2001
From: Bereket Engida <86073083+Bekacru@users.noreply.github.com>
Date: Sun, 8 Dec 2024 10:54:58 +0300
Subject: [PATCH] feat: error codes (#771)

---
 .../better-auth/src/api/routes/account.ts     |  5 +-
 .../src/api/routes/email-verification.ts      |  3 +-
 .../src/api/routes/forget-password.ts         |  5 +-
 .../better-auth/src/api/routes/session.ts     |  3 +-
 .../better-auth/src/api/routes/sign-in.ts     | 28 +++++------
 .../better-auth/src/api/routes/sign-out.ts    |  3 +-
 .../better-auth/src/api/routes/sign-up.ts     | 48 +++++++++---------
 .../better-auth/src/api/routes/update-user.ts | 23 ++++-----
 packages/better-auth/src/auth.ts              | 17 ++++++-
 .../better-auth/src/client/react/index.ts     |  7 ++-
 .../better-auth/src/client/solid/index.ts     |  9 ++--
 .../better-auth/src/client/svelte/index.ts    |  7 ++-
 packages/better-auth/src/client/types.ts      | 11 +++++
 packages/better-auth/src/client/vanilla.ts    |  9 ++--
 packages/better-auth/src/client/vue/index.ts  |  7 ++-
 packages/better-auth/src/error/codes.ts       | 22 +++++++++
 .../src/plugins/admin/admin.test.ts           | 49 +++++++++----------
 .../better-auth/src/plugins/admin/index.ts    | 17 +++++--
 .../src/plugins/anonymous/anon.test.ts        | 29 +++++------
 .../src/plugins/anonymous/index.ts            | 15 ++++--
 .../src/plugins/email-otp/index.ts            | 17 +++++--
 .../src/plugins/generic-oauth/index.ts        |  6 ++-
 .../src/plugins/magic-link/index.ts           | 13 +++--
 .../src/plugins/multi-session/index.ts        | 11 +++--
 .../src/plugins/organization/error-codes.ts   | 34 +++++++++++++
 .../src/plugins/organization/organization.ts  |  7 ++-
 .../organization/routes/crud-invites.ts       | 43 +++++++++-------
 .../organization/routes/crud-members.ts       | 35 +++++++------
 .../plugins/organization/routes/crud-org.ts   | 30 +++++++-----
 .../better-auth/src/plugins/passkey/index.ts  | 36 +++++++++-----
 .../src/plugins/phone-number/index.ts         | 33 ++++++++-----
 .../plugins/two-factor/backup-codes/index.ts  |  9 ++--
 .../src/plugins/two-factor/error-code.ts      |  8 +++
 .../src/plugins/two-factor/index.ts           |  4 +-
 .../src/plugins/two-factor/otp/index.ts       |  7 +--
 .../src/plugins/two-factor/totp/index.ts      |  7 +--
 .../better-auth/src/plugins/username/index.ts | 20 +++++---
 packages/better-auth/src/types/plugins.ts     | 17 ++++++-
 38 files changed, 443 insertions(+), 211 deletions(-)
 create mode 100644 packages/better-auth/src/error/codes.ts
 create mode 100644 packages/better-auth/src/plugins/organization/error-codes.ts
 create mode 100644 packages/better-auth/src/plugins/two-factor/error-code.ts

diff --git a/packages/better-auth/src/api/routes/account.ts b/packages/better-auth/src/api/routes/account.ts
index cb74d496e5..2df6307771 100644
--- a/packages/better-auth/src/api/routes/account.ts
+++ b/packages/better-auth/src/api/routes/account.ts
@@ -4,6 +4,7 @@ import { socialProviderList } from "../../social-providers";
 import { APIError } from "better-call";
 import { generateState } from "../../oauth2";
 import { sessionMiddleware } from "./session";
+import { BASE_ERROR_CODES } from "../../error/codes";
 
 export const listUserAccounts = createAuthEndpoint(
 	"/list-accounts",
@@ -123,7 +124,7 @@ export const linkSocialAccount = createAuthEndpoint(
 		);
 		if (existingAccount) {
 			throw new APIError("BAD_REQUEST", {
-				message: "Social Account is already linked.",
+				message: BASE_ERROR_CODES.SOCIAL_ACCOUNT_ALREADY_LINKED,
 			});
 		}
 		const provider = c.context.socialProviders.find(
@@ -137,7 +138,7 @@ export const linkSocialAccount = createAuthEndpoint(
 				},
 			);
 			throw new APIError("NOT_FOUND", {
-				message: "Provider not found",
+				message: BASE_ERROR_CODES.PROVIDER_NOT_FOUND,
 			});
 		}
 		const state = await generateState(c, {
diff --git a/packages/better-auth/src/api/routes/email-verification.ts b/packages/better-auth/src/api/routes/email-verification.ts
index eb1fd945fd..c1b0297797 100644
--- a/packages/better-auth/src/api/routes/email-verification.ts
+++ b/packages/better-auth/src/api/routes/email-verification.ts
@@ -6,6 +6,7 @@ import { APIError } from "better-call";
 import { getSessionFromCtx } from "./session";
 import { setSessionCookie } from "../../cookies";
 import type { GenericEndpointContext, User } from "../../types";
+import { BASE_ERROR_CODES } from "../../error/codes";
 
 export async function createEmailVerificationToken(
 	secret: string,
@@ -143,7 +144,7 @@ export const sendVerificationEmail = createAuthEndpoint(
 		const user = await ctx.context.internalAdapter.findUserByEmail(email);
 		if (!user) {
 			throw new APIError("BAD_REQUEST", {
-				message: "User not found",
+				message: BASE_ERROR_CODES.USER_NOT_FOUND,
 			});
 		}
 		await sendVerificationEmailFn(ctx, user.user);
diff --git a/packages/better-auth/src/api/routes/forget-password.ts b/packages/better-auth/src/api/routes/forget-password.ts
index 46b878a652..839334440c 100644
--- a/packages/better-auth/src/api/routes/forget-password.ts
+++ b/packages/better-auth/src/api/routes/forget-password.ts
@@ -4,6 +4,7 @@ import { APIError } from "better-call";
 import type { AuthContext } from "../../init";
 import { getDate } from "../../utils/date";
 import { generateId } from "../../utils";
+import { BASE_ERROR_CODES } from "../../error/codes";
 
 function redirectError(
 	ctx: AuthContext,
@@ -241,7 +242,7 @@ export const resetPassword = createAuthEndpoint(
 				: "");
 		if (!token) {
 			throw new APIError("BAD_REQUEST", {
-				message: "Token not found",
+				message: BASE_ERROR_CODES.INVALID_TOKEN,
 			});
 		}
 
@@ -252,7 +253,7 @@ export const resetPassword = createAuthEndpoint(
 			await ctx.context.internalAdapter.findVerificationValue(id);
 		if (!verification || verification.expiresAt < new Date()) {
 			throw new APIError("BAD_REQUEST", {
-				message: "Invalid token",
+				message: BASE_ERROR_CODES.INVALID_TOKEN,
 			});
 		}
 		await ctx.context.internalAdapter.deleteVerificationValue(verification.id);
diff --git a/packages/better-auth/src/api/routes/session.ts b/packages/better-auth/src/api/routes/session.ts
index 4ae9f46f6e..bbebca4edf 100644
--- a/packages/better-auth/src/api/routes/session.ts
+++ b/packages/better-auth/src/api/routes/session.ts
@@ -14,6 +14,7 @@ import type {
 } from "../../types";
 import { hmac } from "../../crypto/hash";
 import { safeJSONParse } from "../../utils/json";
+import { BASE_ERROR_CODES } from "../../error/codes";
 
 export const getSession = <Option extends BetterAuthOptions>() =>
 	createAuthEndpoint(
@@ -238,7 +239,7 @@ export const getSession = <Option extends BetterAuthOptions>() =>
 			} catch (error) {
 				ctx.context.logger.error("INTERNAL_SERVER_ERROR", error);
 				throw new APIError("INTERNAL_SERVER_ERROR", {
-					message: "internal server error",
+					message: BASE_ERROR_CODES.FAILED_TO_GET_SESSION,
 				});
 			}
 		},
diff --git a/packages/better-auth/src/api/routes/sign-in.ts b/packages/better-auth/src/api/routes/sign-in.ts
index bde0ce8030..ad24358476 100644
--- a/packages/better-auth/src/api/routes/sign-in.ts
+++ b/packages/better-auth/src/api/routes/sign-in.ts
@@ -6,6 +6,7 @@ import { socialProviderList } from "../../social-providers";
 import { createEmailVerificationToken } from "./email-verification";
 import { generateState } from "../../utils";
 import { handleOAuthUserInfo } from "../../oauth2/link-account";
+import { BASE_ERROR_CODES } from "../../error/codes";
 
 export const signInSocial = createAuthEndpoint(
 	"/sign-in/social",
@@ -163,7 +164,7 @@ export const signInSocial = createAuthEndpoint(
 				},
 			);
 			throw new APIError("NOT_FOUND", {
-				message: "Provider not found",
+				message: BASE_ERROR_CODES.PROVIDER_NOT_FOUND,
 			});
 		}
 
@@ -176,7 +177,7 @@ export const signInSocial = createAuthEndpoint(
 					},
 				);
 				throw new APIError("NOT_FOUND", {
-					message: "Provider does not support id token verification",
+					message: BASE_ERROR_CODES.ID_TOKEN_NOT_SUPPORTED,
 				});
 			}
 			const { token, nonce } = c.body.idToken;
@@ -186,7 +187,7 @@ export const signInSocial = createAuthEndpoint(
 					provider: c.body.provider,
 				});
 				throw new APIError("UNAUTHORIZED", {
-					message: "Invalid id token",
+					message: BASE_ERROR_CODES.INVALID_TOKEN,
 				});
 			}
 			const userInfo = await provider.getUserInfo({
@@ -199,7 +200,7 @@ export const signInSocial = createAuthEndpoint(
 					provider: c.body.provider,
 				});
 				throw new APIError("UNAUTHORIZED", {
-					message: "Failed to get user info",
+					message: BASE_ERROR_CODES.FAILED_TO_GET_USER_INFO,
 				});
 			}
 			if (!userInfo.user.email) {
@@ -207,7 +208,7 @@ export const signInSocial = createAuthEndpoint(
 					provider: c.body.provider,
 				});
 				throw new APIError("UNAUTHORIZED", {
-					message: "User email not found",
+					message: BASE_ERROR_CODES.USER_EMAIL_NOT_FOUND,
 				});
 			}
 			const data = await handleOAuthUserInfo(c, {
@@ -337,7 +338,7 @@ export const signInEmail = createAuthEndpoint(
 		const isValidEmail = z.string().email().safeParse(email);
 		if (!isValidEmail.success) {
 			throw new APIError("BAD_REQUEST", {
-				message: "Invalid email",
+				message: BASE_ERROR_CODES.INVALID_EMAIL,
 			});
 		}
 		const user = await ctx.context.internalAdapter.findUserByEmail(email, {
@@ -348,7 +349,7 @@ export const signInEmail = createAuthEndpoint(
 			await ctx.context.password.hash(password);
 			ctx.context.logger.error("User not found", { email });
 			throw new APIError("UNAUTHORIZED", {
-				message: "Invalid email or password",
+				message: BASE_ERROR_CODES.INVALID_EMAIL_OR_PASSWORD,
 			});
 		}
 
@@ -358,14 +359,14 @@ export const signInEmail = createAuthEndpoint(
 		if (!credentialAccount) {
 			ctx.context.logger.error("Credential account not found", { email });
 			throw new APIError("UNAUTHORIZED", {
-				message: "Invalid email or password",
+				message: BASE_ERROR_CODES.INVALID_EMAIL_OR_PASSWORD,
 			});
 		}
 		const currentPassword = credentialAccount?.password;
 		if (!currentPassword) {
 			ctx.context.logger.error("Password not found", { email });
 			throw new APIError("UNAUTHORIZED", {
-				message: "Unexpected error",
+				message: BASE_ERROR_CODES.INVALID_EMAIL_OR_PASSWORD,
 			});
 		}
 		const validPassword = await ctx.context.password.verify({
@@ -375,7 +376,7 @@ export const signInEmail = createAuthEndpoint(
 		if (!validPassword) {
 			ctx.context.logger.error("Invalid password");
 			throw new APIError("UNAUTHORIZED", {
-				message: "Invalid email or password",
+				message: BASE_ERROR_CODES.INVALID_EMAIL_OR_PASSWORD,
 			});
 		}
 
@@ -385,7 +386,7 @@ export const signInEmail = createAuthEndpoint(
 		) {
 			if (!ctx.context.options?.emailVerification?.sendVerificationEmail) {
 				throw new APIError("UNAUTHORIZED", {
-					message: "Email is not verified.",
+					message: BASE_ERROR_CODES.EMAIL_NOT_VERIFIED,
 				});
 			}
 			const token = await createEmailVerificationToken(
@@ -405,8 +406,7 @@ export const signInEmail = createAuthEndpoint(
 			);
 			ctx.context.logger.error("Email not verified", { email });
 			throw new APIError("FORBIDDEN", {
-				message:
-					"Email is not verified. Check your email for a verification link",
+				message: BASE_ERROR_CODES.EMAIL_NOT_VERIFIED,
 			});
 		}
 
@@ -419,7 +419,7 @@ export const signInEmail = createAuthEndpoint(
 		if (!session) {
 			ctx.context.logger.error("Failed to create session");
 			throw new APIError("UNAUTHORIZED", {
-				message: "Failed to create session",
+				message: BASE_ERROR_CODES.FAILED_TO_CREATE_SESSION,
 			});
 		}
 
diff --git a/packages/better-auth/src/api/routes/sign-out.ts b/packages/better-auth/src/api/routes/sign-out.ts
index d5abdac145..8d596e912c 100644
--- a/packages/better-auth/src/api/routes/sign-out.ts
+++ b/packages/better-auth/src/api/routes/sign-out.ts
@@ -2,6 +2,7 @@ import { z } from "zod";
 import { createAuthEndpoint } from "../call";
 import { deleteSessionCookie } from "../../cookies";
 import { APIError } from "better-call";
+import { BASE_ERROR_CODES } from "../../error/codes";
 
 export const signOut = createAuthEndpoint(
 	"/sign-out",
@@ -39,7 +40,7 @@ export const signOut = createAuthEndpoint(
 		if (!sessionCookieToken) {
 			deleteSessionCookie(ctx);
 			throw new APIError("BAD_REQUEST", {
-				message: "Session not found",
+				message: BASE_ERROR_CODES.FAILED_TO_GET_SESSION,
 			});
 		}
 		await ctx.context.internalAdapter.deleteSession(sessionCookieToken);
diff --git a/packages/better-auth/src/api/routes/sign-up.ts b/packages/better-auth/src/api/routes/sign-up.ts
index ca7a22a99c..4b9556b084 100644
--- a/packages/better-auth/src/api/routes/sign-up.ts
+++ b/packages/better-auth/src/api/routes/sign-up.ts
@@ -12,6 +12,7 @@ import type {
 } from "../../types";
 import type { toZod } from "../../types/to-zod";
 import { parseUserInput } from "../../db/schema";
+import { BASE_ERROR_CODES } from "../../error/codes";
 
 export const signUpEmail = <O extends BetterAuthOptions>() =>
 	createAuthEndpoint(
@@ -102,13 +103,7 @@ export const signUpEmail = <O extends BetterAuthOptions>() =>
 
 			if (!isValidEmail.success) {
 				throw new APIError("BAD_REQUEST", {
-					message: "Invalid email",
-				});
-			}
-
-			if (typeof password !== "string") {
-				throw new APIError("BAD_REQUEST", {
-					message: "Password must be a string",
+					message: BASE_ERROR_CODES.INVALID_EMAIL,
 				});
 			}
 
@@ -116,7 +111,7 @@ export const signUpEmail = <O extends BetterAuthOptions>() =>
 			if (password.length < minPasswordLength) {
 				ctx.context.logger.error("Password is too short");
 				throw new APIError("BAD_REQUEST", {
-					message: "Password is too short",
+					message: BASE_ERROR_CODES.PASSWORD_TOO_SHORT,
 				});
 			}
 
@@ -124,14 +119,14 @@ export const signUpEmail = <O extends BetterAuthOptions>() =>
 			if (password.length > maxPasswordLength) {
 				ctx.context.logger.error("Password is too long");
 				throw new APIError("BAD_REQUEST", {
-					message: "Password is too long",
+					message: BASE_ERROR_CODES.PASSWORD_TOO_LONG,
 				});
 			}
 			const dbUser = await ctx.context.internalAdapter.findUserByEmail(email);
 			if (dbUser?.user) {
 				ctx.context.logger.info(`Sign-up attempt for existing email: ${email}`);
 				throw new APIError("UNPROCESSABLE_ENTITY", {
-					message: "User with this email already exists",
+					message: BASE_ERROR_CODES.USER_ALREADY_EXISTS,
 				});
 			}
 
@@ -139,21 +134,30 @@ export const signUpEmail = <O extends BetterAuthOptions>() =>
 				ctx.context.options,
 				additionalFields as any,
 			);
-			const createdUser = await ctx.context.internalAdapter.createUser({
-				email: email.toLowerCase(),
-				name,
-				image,
-				...additionalData,
-				emailVerified: false,
-			});
-			if (!createdUser) {
-				throw new APIError("BAD_REQUEST", {
-					message: "Failed to create user",
+			let createdUser: User;
+			try {
+				createdUser = await ctx.context.internalAdapter.createUser({
+					email: email.toLowerCase(),
+					name,
+					image,
+					...additionalData,
+					emailVerified: false,
+				});
+				if (!createdUser) {
+					throw new APIError("BAD_REQUEST", {
+						message: BASE_ERROR_CODES.FAILED_TO_CREATE_USER,
+					});
+				}
+			} catch (e) {
+				ctx.context.logger.error("Failed to create user", e);
+				throw new APIError("UNPROCESSABLE_ENTITY", {
+					message: BASE_ERROR_CODES.FAILED_TO_CREATE_USER,
+					details: e,
 				});
 			}
 			if (!createdUser) {
 				throw new APIError("UNPROCESSABLE_ENTITY", {
-					message: "Failed to create user",
+					message: BASE_ERROR_CODES.FAILED_TO_CREATE_USER,
 				});
 			}
 			/**
@@ -202,7 +206,7 @@ export const signUpEmail = <O extends BetterAuthOptions>() =>
 			);
 			if (!session) {
 				throw new APIError("BAD_REQUEST", {
-					message: "Failed to create session",
+					message: BASE_ERROR_CODES.FAILED_TO_CREATE_SESSION,
 				});
 			}
 			await setSessionCookie(ctx, {
diff --git a/packages/better-auth/src/api/routes/update-user.ts b/packages/better-auth/src/api/routes/update-user.ts
index 5c996f0d85..1fe826c1b2 100644
--- a/packages/better-auth/src/api/routes/update-user.ts
+++ b/packages/better-auth/src/api/routes/update-user.ts
@@ -13,6 +13,7 @@ import type { toZod } from "../../types/to-zod";
 import type { AdditionalUserFieldsInput, BetterAuthOptions } from "../../types";
 import { parseUserInput } from "../../db/schema";
 import { alphabet, generateRandomString } from "../../crypto";
+import { BASE_ERROR_CODES } from "../../error/codes";
 
 export const updateUser = <O extends BetterAuthOptions>() =>
 	createAuthEndpoint(
@@ -78,7 +79,7 @@ export const updateUser = <O extends BetterAuthOptions>() =>
 
 			if (body.email) {
 				throw new APIError("BAD_REQUEST", {
-					message: "You can't update email",
+					message: BASE_ERROR_CODES.EMAIL_CAN_NOT_BE_UPDATED,
 				});
 			}
 			const { name, image, ...rest } = body;
@@ -173,7 +174,7 @@ export const changePassword = createAuthEndpoint(
 		if (newPassword.length < minPasswordLength) {
 			ctx.context.logger.error("Password is too short");
 			throw new APIError("BAD_REQUEST", {
-				message: "Password is too short",
+				message: BASE_ERROR_CODES.PASSWORD_TOO_SHORT,
 			});
 		}
 
@@ -182,7 +183,7 @@ export const changePassword = createAuthEndpoint(
 		if (newPassword.length > maxPasswordLength) {
 			ctx.context.logger.error("Password is too long");
 			throw new APIError("BAD_REQUEST", {
-				message: "Password too long",
+				message: BASE_ERROR_CODES.PASSWORD_TOO_LONG,
 			});
 		}
 
@@ -194,7 +195,7 @@ export const changePassword = createAuthEndpoint(
 		);
 		if (!account || !account.password) {
 			throw new APIError("BAD_REQUEST", {
-				message: "User does not have a password",
+				message: BASE_ERROR_CODES.CREDENTIAL_ACCOUNT_NOT_FOUND,
 			});
 		}
 		const passwordHash = await ctx.context.password.hash(newPassword);
@@ -204,7 +205,7 @@ export const changePassword = createAuthEndpoint(
 		});
 		if (!verify) {
 			throw new APIError("BAD_REQUEST", {
-				message: "Incorrect password",
+				message: BASE_ERROR_CODES.INVALID_PASSWORD,
 			});
 		}
 		await ctx.context.internalAdapter.updateAccount(account.id, {
@@ -218,7 +219,7 @@ export const changePassword = createAuthEndpoint(
 			);
 			if (!newSession) {
 				throw new APIError("INTERNAL_SERVER_ERROR", {
-					message: "Unable to create session",
+					message: BASE_ERROR_CODES.FAILED_TO_GET_SESSION,
 				});
 			}
 			// set the new session cookie
@@ -254,7 +255,7 @@ export const setPassword = createAuthEndpoint(
 		if (newPassword.length < minPasswordLength) {
 			ctx.context.logger.error("Password is too short");
 			throw new APIError("BAD_REQUEST", {
-				message: "Password is too short",
+				message: BASE_ERROR_CODES.PASSWORD_TOO_SHORT,
 			});
 		}
 
@@ -263,7 +264,7 @@ export const setPassword = createAuthEndpoint(
 		if (newPassword.length > maxPasswordLength) {
 			ctx.context.logger.error("Password is too long");
 			throw new APIError("BAD_REQUEST", {
-				message: "Password too long",
+				message: BASE_ERROR_CODES.PASSWORD_TOO_LONG,
 			});
 		}
 
@@ -382,7 +383,7 @@ export const deleteUserCallback = createAuthEndpoint(
 		const session = await getSessionFromCtx(ctx);
 		if (!session) {
 			throw new APIError("NOT_FOUND", {
-				message: "No session found",
+				message: BASE_ERROR_CODES.FAILED_TO_GET_USER_INFO,
 			});
 		}
 		const token = await ctx.context.internalAdapter.findVerificationValue(
@@ -393,12 +394,12 @@ export const deleteUserCallback = createAuthEndpoint(
 				await ctx.context.internalAdapter.deleteVerificationValue(token.id);
 			}
 			throw new APIError("NOT_FOUND", {
-				message: "Invalid token",
+				message: BASE_ERROR_CODES.INVALID_TOKEN,
 			});
 		}
 		if (token.value !== session.user.id) {
 			throw new APIError("NOT_FOUND", {
-				message: "Invalid token",
+				message: BASE_ERROR_CODES.INVALID_TOKEN,
 			});
 		}
 		const beforeDelete = ctx.context.options.user.deleteUser?.beforeDelete;
diff --git a/packages/better-auth/src/auth.ts b/packages/better-auth/src/auth.ts
index 37b8b97381..9946ed620f 100644
--- a/packages/better-auth/src/auth.ts
+++ b/packages/better-auth/src/auth.ts
@@ -2,6 +2,7 @@ import { getEndpoints, router } from "./api";
 import { init } from "./init";
 import type { BetterAuthOptions } from "./types/options";
 import type {
+	InferPluginErrorCodes,
 	InferPluginTypes,
 	InferSession,
 	InferUser,
@@ -9,11 +10,20 @@ import type {
 } from "./types";
 import { getBaseURL } from "./utils/url";
 import type { FilterActions, InferAPI } from "./types/api";
+import { BASE_ERROR_CODES } from "./error/codes";
 
 export const betterAuth = <O extends BetterAuthOptions>(options: O) => {
 	const authContext = init(options);
 	const { api } = getEndpoints(authContext, options);
-
+	const errorCodes = options.plugins?.reduce((acc, plugin) => {
+		if (plugin.$ERROR_CODES) {
+			return {
+				...acc,
+				...plugin.$ERROR_CODES,
+			};
+		}
+		return acc;
+	}, {});
 	return {
 		handler: async (request: Request) => {
 			const ctx = await authContext;
@@ -42,6 +52,10 @@ export const betterAuth = <O extends BetterAuthOptions>(options: O) => {
 				user: PrettifyDeep<InferUser<O>>;
 			};
 		} & InferPluginTypes<O>,
+		$ErrorCodes: {
+			...errorCodes,
+			...BASE_ERROR_CODES,
+		} as InferPluginErrorCodes<O> & typeof BASE_ERROR_CODES,
 	};
 };
 
@@ -49,4 +63,5 @@ export type Auth = {
 	handler: (request: Request) => Promise<Response>;
 	api: FilterActions<ReturnType<typeof router>["endpoints"]>;
 	options: BetterAuthOptions;
+	$ERROR_CODES: typeof BASE_ERROR_CODES;
 };
diff --git a/packages/better-auth/src/client/react/index.ts b/packages/better-auth/src/client/react/index.ts
index 018f713532..2ca871d554 100644
--- a/packages/better-auth/src/client/react/index.ts
+++ b/packages/better-auth/src/client/react/index.ts
@@ -4,17 +4,19 @@ import type {
 	ClientOptions,
 	InferActions,
 	InferClientAPI,
+	InferErrorCodes,
 	InferSessionFromClient,
 	InferUserFromClient,
 	IsSignal,
 } from "../types";
 import { createDynamicPathProxy } from "../proxy";
-import type { UnionToIntersection } from "../../types/helper";
+import type { PrettifyDeep, UnionToIntersection } from "../../types/helper";
 import type {
 	BetterFetchError,
 	BetterFetchResponse,
 } from "@better-fetch/fetch";
 import { useStore } from "./react-store";
+import type { BASE_ERROR_CODES } from "../../error/codes";
 
 function getAtomKey(str: string) {
 	return `use${capitalizeFirstLetter(str)}`;
@@ -92,6 +94,9 @@ export function createAuthClient<Option extends ClientOptions>(
 			};
 			$fetch: typeof $fetch;
 			$store: typeof $store;
+			$ERROR_CODES: PrettifyDeep<
+				InferErrorCodes<Option> & typeof BASE_ERROR_CODES
+			>;
 		};
 }
 
diff --git a/packages/better-auth/src/client/solid/index.ts b/packages/better-auth/src/client/solid/index.ts
index 400bdbedcc..2064b60cd3 100644
--- a/packages/better-auth/src/client/solid/index.ts
+++ b/packages/better-auth/src/client/solid/index.ts
@@ -6,17 +6,17 @@ import type {
 	ClientOptions,
 	InferActions,
 	InferClientAPI,
-	InferSessionFromClient,
-	InferUserFromClient,
+	InferErrorCodes,
 	IsSignal,
 } from "../types";
 import type { Accessor } from "solid-js";
-import type { UnionToIntersection } from "../../types/helper";
+import type { PrettifyDeep, UnionToIntersection } from "../../types/helper";
 import type {
 	BetterFetchError,
 	BetterFetchResponse,
 } from "@better-fetch/fetch";
 import { useStore } from "./solid-store";
+import type { BASE_ERROR_CODES } from "../../error/codes";
 
 function getAtomKey(str: string) {
 	return `use${capitalizeFirstLetter(str)}`;
@@ -84,5 +84,8 @@ export function createAuthClient<Option extends ClientOptions>(
 				Session: NonNullable<Session>;
 			};
 			$fetch: typeof $fetch;
+			$ERROR_CODES: PrettifyDeep<
+				InferErrorCodes<Option> & typeof BASE_ERROR_CODES
+			>;
 		};
 }
diff --git a/packages/better-auth/src/client/svelte/index.ts b/packages/better-auth/src/client/svelte/index.ts
index 1e7bb2bf81..c25d1f027b 100644
--- a/packages/better-auth/src/client/svelte/index.ts
+++ b/packages/better-auth/src/client/svelte/index.ts
@@ -5,17 +5,19 @@ import type {
 	ClientOptions,
 	InferActions,
 	InferClientAPI,
+	InferErrorCodes,
 	InferSessionFromClient,
 	InferUserFromClient,
 	IsSignal,
 } from "../types";
 import { createDynamicPathProxy } from "../proxy";
-import type { UnionToIntersection } from "../../types/helper";
+import type { PrettifyDeep, UnionToIntersection } from "../../types/helper";
 import type { Atom } from "nanostores";
 import type {
 	BetterFetchError,
 	BetterFetchResponse,
 } from "@better-fetch/fetch";
+import type { BASE_ERROR_CODES } from "../../error/codes";
 
 type InferResolvedHooks<O extends ClientOptions> = O["plugins"] extends Array<
 	infer Plugin
@@ -83,5 +85,8 @@ export function createAuthClient<Option extends ClientOptions>(
 			$Infer: {
 				Session: NonNullable<Session>;
 			};
+			$ERROR_CODES: PrettifyDeep<
+				InferErrorCodes<Option> & typeof BASE_ERROR_CODES
+			>;
 		};
 }
diff --git a/packages/better-auth/src/client/types.ts b/packages/better-auth/src/client/types.ts
index caa79898fb..359eadd4bc 100644
--- a/packages/better-auth/src/client/types.ts
+++ b/packages/better-auth/src/client/types.ts
@@ -97,6 +97,17 @@ export type InferActions<O extends ClientOptions> = O["plugins"] extends Array<
 				: {}
 		>
 	: {};
+
+export type InferErrorCodes<O extends ClientOptions> =
+	O["plugins"] extends Array<infer Plugin>
+		? UnionToIntersection<
+				Plugin extends BetterAuthClientPlugin
+					? Plugin["$InferServerPlugin"] extends BetterAuthPlugin
+						? Plugin["$InferServerPlugin"]["$ERROR_CODES"]
+						: {}
+					: {}
+			>
+		: {};
 /**
  * signals are just used to recall a computed value.
  * as a convention they start with "$"
diff --git a/packages/better-auth/src/client/vanilla.ts b/packages/better-auth/src/client/vanilla.ts
index 2c7f3428ee..ffbc555d19 100644
--- a/packages/better-auth/src/client/vanilla.ts
+++ b/packages/better-auth/src/client/vanilla.ts
@@ -5,17 +5,17 @@ import type {
 	ClientOptions,
 	InferActions,
 	InferClientAPI,
-	InferSessionFromClient,
-	InferUserFromClient,
+	InferErrorCodes,
 	IsSignal,
 } from "./types";
 import { createDynamicPathProxy } from "./proxy";
-import type { UnionToIntersection } from "../types/helper";
+import type { PrettifyDeep, UnionToIntersection } from "../types/helper";
 import type { Atom } from "nanostores";
 import type {
 	BetterFetchError,
 	BetterFetchResponse,
 } from "@better-fetch/fetch";
+import type { BASE_ERROR_CODES } from "../error/codes";
 
 type InferResolvedHooks<O extends ClientOptions> = O["plugins"] extends Array<
 	infer Plugin
@@ -82,5 +82,8 @@ export function createAuthClient<Option extends ClientOptions>(
 			$Infer: {
 				Session: NonNullable<Session>;
 			};
+			$ERROR_CODES: PrettifyDeep<
+				InferErrorCodes<Option> & typeof BASE_ERROR_CODES
+			>;
 		};
 }
diff --git a/packages/better-auth/src/client/vue/index.ts b/packages/better-auth/src/client/vue/index.ts
index 8c56d952bb..7cf87a1af7 100644
--- a/packages/better-auth/src/client/vue/index.ts
+++ b/packages/better-auth/src/client/vue/index.ts
@@ -7,14 +7,16 @@ import type {
 	ClientOptions,
 	InferActions,
 	InferClientAPI,
+	InferErrorCodes,
 	IsSignal,
 } from "../types";
 import { createDynamicPathProxy } from "../proxy";
-import type { UnionToIntersection } from "../../types/helper";
+import type { PrettifyDeep, UnionToIntersection } from "../../types/helper";
 import type {
 	BetterFetchError,
 	BetterFetchResponse,
 } from "@better-fetch/fetch";
+import type { BASE_ERROR_CODES } from "../../error/codes";
 
 function getAtomKey(str: string) {
 	return `use${capitalizeFirstLetter(str)}`;
@@ -125,5 +127,8 @@ export function createAuthClient<Option extends ClientOptions>(
 			};
 			$fetch: typeof $fetch;
 			$store: typeof $store;
+			$ERROR_CODES: PrettifyDeep<
+				InferErrorCodes<Option> & typeof BASE_ERROR_CODES
+			>;
 		};
 }
diff --git a/packages/better-auth/src/error/codes.ts b/packages/better-auth/src/error/codes.ts
new file mode 100644
index 0000000000..b34062c878
--- /dev/null
+++ b/packages/better-auth/src/error/codes.ts
@@ -0,0 +1,22 @@
+export const BASE_ERROR_CODES = {
+	USER_NOT_FOUND: "User not found",
+	FAILED_TO_CREATE_USER: "Failed to create user",
+	FAILED_TO_CREATE_SESSION: "Failed to create session",
+	FAILED_TO_UPDATE_USER: "Failed to update user",
+	FAILED_TO_GET_SESSION: "Failed to get session",
+	INVALID_PASSWORD: "Invalid password",
+	INVALID_EMAIL: "Invalid email",
+	INVALID_EMAIL_OR_PASSWORD: "Invalid email or password",
+	SOCIAL_ACCOUNT_ALREADY_LINKED: "Social account already linked",
+	PROVIDER_NOT_FOUND: "Provider not found",
+	INVALID_TOKEN: "invalid token",
+	ID_TOKEN_NOT_SUPPORTED: "id_token not supported",
+	FAILED_TO_GET_USER_INFO: "Failed to get user info",
+	USER_EMAIL_NOT_FOUND: "User email not found",
+	EMAIL_NOT_VERIFIED: "Email not verified",
+	PASSWORD_TOO_SHORT: "Password too short",
+	PASSWORD_TOO_LONG: "Password too long",
+	USER_ALREADY_EXISTS: "User already exists",
+	EMAIL_CAN_NOT_BE_UPDATED: "Email can not be updated",
+	CREDENTIAL_ACCOUNT_NOT_FOUND: "Credential account not found",
+};
diff --git a/packages/better-auth/src/plugins/admin/admin.test.ts b/packages/better-auth/src/plugins/admin/admin.test.ts
index 00db843717..24d0ae9791 100644
--- a/packages/better-auth/src/plugins/admin/admin.test.ts
+++ b/packages/better-auth/src/plugins/admin/admin.test.ts
@@ -4,36 +4,35 @@ import { admin, type UserWithRole } from ".";
 import { adminClient } from "./client";
 
 describe("Admin plugin", async () => {
-	const { client, auth, signInWithTestUser, signInWithUser } =
-		await getTestInstance(
-			{
-				plugins: [admin()],
-				databaseHooks: {
-					user: {
-						create: {
-							before: async (user) => {
-								if (user.name === "Admin") {
-									return {
-										data: {
-											...user,
-											role: "admin",
-										},
-									};
-								}
-							},
+	const { client, signInWithTestUser, signInWithUser } = await getTestInstance(
+		{
+			plugins: [admin()],
+			databaseHooks: {
+				user: {
+					create: {
+						before: async (user) => {
+							if (user.name === "Admin") {
+								return {
+									data: {
+										...user,
+										role: "admin",
+									},
+								};
+							}
 						},
 					},
 				},
 			},
-			{
-				testUser: {
-					name: "Admin",
-				},
-				clientOptions: {
-					plugins: [adminClient()],
-				},
+		},
+		{
+			testUser: {
+				name: "Admin",
 			},
-		);
+			clientOptions: {
+				plugins: [adminClient()],
+			},
+		},
+	);
 	const { headers: adminHeaders } = await signInWithTestUser();
 	let newUser: UserWithRole | undefined;
 
diff --git a/packages/better-auth/src/plugins/admin/index.ts b/packages/better-auth/src/plugins/admin/index.ts
index 1d45823dee..509b47e66f 100644
--- a/packages/better-auth/src/plugins/admin/index.ts
+++ b/packages/better-auth/src/plugins/admin/index.ts
@@ -74,6 +74,14 @@ export const admin = <O extends AdminOptions>(options?: O) => {
 		adminRole: "admin",
 		...options,
 	};
+	const ERROR_CODES = {
+		FAILED_TO_CREATE_USER: "Failed to create user",
+		USER_ALREADY_EXISTS: "User already exists",
+		USER_NOT_FOUND: "User not found",
+		YOU_CANNOT_BAN_YOURSELF: "You cannot ban yourself",
+		ONLY_ADMINS_CAN_ACCESS_THIS_ENDPOINT:
+			"Only admins can access this endpoint",
+	} as const;
 	const adminMiddleware = createAuthMiddleware(async (ctx) => {
 		const session = await getSessionFromCtx(ctx);
 		if (!session?.session) {
@@ -278,7 +286,7 @@ export const admin = <O extends AdminOptions>(options?: O) => {
 					);
 					if (existUser) {
 						throw new APIError("BAD_REQUEST", {
-							message: "User already exists",
+							message: ERROR_CODES.USER_ALREADY_EXISTS,
 						});
 					}
 					const user =
@@ -291,7 +299,7 @@ export const admin = <O extends AdminOptions>(options?: O) => {
 
 					if (!user) {
 						throw new APIError("INTERNAL_SERVER_ERROR", {
-							message: "Failed to create user",
+							message: ERROR_CODES.FAILED_TO_CREATE_USER,
 						});
 					}
 					const hashedPassword = await ctx.context.password.hash(
@@ -589,7 +597,7 @@ export const admin = <O extends AdminOptions>(options?: O) => {
 				async (ctx) => {
 					if (ctx.body.userId === ctx.context.session.user.id) {
 						throw new APIError("BAD_REQUEST", {
-							message: "You cannot ban yourself",
+							message: ERROR_CODES.YOU_CANNOT_BAN_YOURSELF,
 						});
 					}
 					const user = await ctx.context.internalAdapter.updateUser(
@@ -674,7 +682,7 @@ export const admin = <O extends AdminOptions>(options?: O) => {
 					);
 					if (!session) {
 						throw new APIError("INTERNAL_SERVER_ERROR", {
-							message: "Failed to create session",
+							message: ERROR_CODES.FAILED_TO_CREATE_USER,
 						});
 					}
 					await setSessionCookie(
@@ -821,6 +829,7 @@ export const admin = <O extends AdminOptions>(options?: O) => {
 				},
 			),
 		},
+		$ERROR_CODES: ERROR_CODES,
 		schema: mergeSchema(schema, opts.schema),
 	} satisfies BetterAuthPlugin;
 };
diff --git a/packages/better-auth/src/plugins/anonymous/anon.test.ts b/packages/better-auth/src/plugins/anonymous/anon.test.ts
index 56caf3b0bd..2af18aa95e 100644
--- a/packages/better-auth/src/plugins/anonymous/anon.test.ts
+++ b/packages/better-auth/src/plugins/anonymous/anon.test.ts
@@ -6,22 +6,23 @@ import { anonymousClient } from "./client";
 
 describe("anonymous", async () => {
 	const linkAccountFn = vi.fn();
-	const { customFetchImpl, sessionSetter, testUser } = await getTestInstance({
-		plugins: [
-			anonymous({
-				async onLinkAccount(data) {
-					linkAccountFn(data);
-				},
-				schema: {
-					user: {
-						fields: {
-							isAnonymous: "is_anon",
+	const { customFetchImpl, auth, sessionSetter, testUser } =
+		await getTestInstance({
+			plugins: [
+				anonymous({
+					async onLinkAccount(data) {
+						linkAccountFn(data);
+					},
+					schema: {
+						user: {
+							fields: {
+								isAnonymous: "is_anon",
+							},
 						},
 					},
-				},
-			}),
-		],
-	});
+				}),
+			],
+		});
 	const headers = new Headers();
 	const client = createAuthClient({
 		plugins: [anonymousClient()],
diff --git a/packages/better-auth/src/plugins/anonymous/index.ts b/packages/better-auth/src/plugins/anonymous/index.ts
index 63441c16fd..2986d7113d 100644
--- a/packages/better-auth/src/plugins/anonymous/index.ts
+++ b/packages/better-auth/src/plugins/anonymous/index.ts
@@ -12,7 +12,6 @@ import type {
 	User,
 } from "../../types";
 import { parseSetCookieHeader, setSessionCookie } from "../../cookies";
-import { z } from "zod";
 import { getOrigin } from "../../utils/url";
 import { mergeSchema } from "../../db/schema";
 
@@ -62,6 +61,12 @@ const schema = {
 } satisfies PluginSchema;
 
 export const anonymous = (options?: AnonymousOptions) => {
+	const ERROR_CODES = {
+		FAILED_TO_CREATE_USER: "Failed to create user",
+		COULD_NOT_CREATE_SESSION: "Could not create session",
+		ANONYMOUS_USERS_CANNOT_SIGN_IN_AGAIN_ANONYMOUSLY:
+			"Anonymous users cannot sign in again anonymously",
+	} as const;
 	return {
 		id: "anonymous",
 		endpoints: {
@@ -113,7 +118,7 @@ export const anonymous = (options?: AnonymousOptions) => {
 						return ctx.json(null, {
 							status: 500,
 							body: {
-								message: "Failed to create user",
+								message: ERROR_CODES.FAILED_TO_CREATE_USER,
 								status: 500,
 							},
 						});
@@ -126,7 +131,7 @@ export const anonymous = (options?: AnonymousOptions) => {
 						return ctx.json(null, {
 							status: 400,
 							body: {
-								message: "Could not create session",
+								message: ERROR_CODES.COULD_NOT_CREATE_SESSION,
 							},
 						});
 					}
@@ -175,7 +180,8 @@ export const anonymous = (options?: AnonymousOptions) => {
 						}
 						if (ctx.path === "/sign-in/anonymous") {
 							throw new APIError("BAD_REQUEST", {
-								message: "Anonymous users cannot sign in again anonymously",
+								message:
+									ERROR_CODES.ANONYMOUS_USERS_CANNOT_SIGN_IN_AGAIN_ANONYMOUSLY,
 							});
 						}
 
@@ -198,5 +204,6 @@ export const anonymous = (options?: AnonymousOptions) => {
 			],
 		},
 		schema: mergeSchema(schema, options?.schema),
+		$ERROR_CODES: ERROR_CODES,
 	} satisfies BetterAuthPlugin;
 };
diff --git a/packages/better-auth/src/plugins/email-otp/index.ts b/packages/better-auth/src/plugins/email-otp/index.ts
index 185f5ae040..4148b9a0da 100644
--- a/packages/better-auth/src/plugins/email-otp/index.ts
+++ b/packages/better-auth/src/plugins/email-otp/index.ts
@@ -1,4 +1,4 @@
-import { z } from "zod";
+import { INVALID, z } from "zod";
 import { APIError, createAuthEndpoint } from "../../api";
 import type { BetterAuthPlugin, User } from "../../types";
 import { alphabet, generateRandomString } from "../../crypto";
@@ -49,6 +49,12 @@ export const emailOTP = (options: EmailOTPOptions) => {
 		otpLength: 6,
 		...options,
 	};
+	const ERROR_CODES = {
+		OTP_EXPIRED: "otp expired",
+		INVALID_OTP: "invalid otp",
+		INVALID_EMAIL: "invalid email",
+		USER_NOT_FOUND: "user not found",
+	} as const;
 	return {
 		id: "email-otp",
 		endpoints: {
@@ -100,7 +106,7 @@ export const emailOTP = (options: EmailOTPOptions) => {
 					const emailRegex = /^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/;
 					if (!emailRegex.test(email)) {
 						throw new APIError("BAD_REQUEST", {
-							message: "Invalid email",
+							message: ERROR_CODES.INVALID_EMAIL,
 						});
 					}
 					const otp = generateRandomString(opts.otpLength, alphabet("0-9"));
@@ -522,7 +528,7 @@ export const emailOTP = (options: EmailOTPOptions) => {
 					const user = await ctx.context.internalAdapter.findUserByEmail(email);
 					if (!user) {
 						throw new APIError("BAD_REQUEST", {
-							message: "User not found",
+							message: ERROR_CODES.USER_NOT_FOUND,
 						});
 					}
 					const verificationValue =
@@ -536,13 +542,13 @@ export const emailOTP = (options: EmailOTPOptions) => {
 							);
 						}
 						throw new APIError("BAD_REQUEST", {
-							message: "Invalid OTP",
+							message: ERROR_CODES.OTP_EXPIRED,
 						});
 					}
 					const otp = ctx.body.otp;
 					if (verificationValue.value !== otp) {
 						throw new APIError("BAD_REQUEST", {
-							message: "Invalid OTP",
+							message: ERROR_CODES.INVALID_OTP,
 						});
 					}
 					await ctx.context.internalAdapter.deleteVerificationValue(
@@ -597,5 +603,6 @@ export const emailOTP = (options: EmailOTPOptions) => {
 				},
 			],
 		},
+		$ERROR_CODES: ERROR_CODES,
 	} satisfies BetterAuthPlugin;
 };
diff --git a/packages/better-auth/src/plugins/generic-oauth/index.ts b/packages/better-auth/src/plugins/generic-oauth/index.ts
index 0151044726..fa52f74ebe 100644
--- a/packages/better-auth/src/plugins/generic-oauth/index.ts
+++ b/packages/better-auth/src/plugins/generic-oauth/index.ts
@@ -166,6 +166,9 @@ async function getUserInfo(
  * A generic OAuth plugin that can be used to add OAuth support to any provider
  */
 export const genericOAuth = (options: GenericOAuthOptions) => {
+	const ERROR_CODES = {
+		INVALID_OAUTH_CONFIGURATION: "Invalid OAuth configuration",
+	} as const;
 	return {
 		id: "generic-oauth",
 		init: (ctx) => {
@@ -352,7 +355,7 @@ export const genericOAuth = (options: GenericOAuthOptions) => {
 					}
 					if (!finalAuthUrl || !finalTokenUrl) {
 						throw new APIError("BAD_REQUEST", {
-							message: "Invalid OAuth configuration.",
+							message: ERROR_CODES.INVALID_OAUTH_CONFIGURATION,
 						});
 					}
 					const { state, codeVerifier } = await generateState(ctx);
@@ -555,5 +558,6 @@ export const genericOAuth = (options: GenericOAuthOptions) => {
 				},
 			),
 		},
+		$ERROR_CODES: ERROR_CODES,
 	} satisfies BetterAuthPlugin;
 };
diff --git a/packages/better-auth/src/plugins/magic-link/index.ts b/packages/better-auth/src/plugins/magic-link/index.ts
index 09ab774508..4117801a97 100644
--- a/packages/better-auth/src/plugins/magic-link/index.ts
+++ b/packages/better-auth/src/plugins/magic-link/index.ts
@@ -4,6 +4,7 @@ import type { BetterAuthPlugin } from "../../types/plugins";
 import { APIError } from "better-call";
 import { setSessionCookie } from "../../cookies";
 import { alphabet, generateRandomString } from "../../crypto";
+import { BASE_ERROR_CODES } from "../../error/codes";
 
 interface MagicLinkOptions {
 	/**
@@ -95,7 +96,7 @@ export const magicLink = (options: MagicLinkOptions) => {
 
 						if (!user) {
 							throw new APIError("BAD_REQUEST", {
-								message: "User not found",
+								message: BASE_ERROR_CODES.USER_NOT_FOUND,
 							});
 						}
 					}
@@ -205,10 +206,12 @@ export const magicLink = (options: MagicLinkOptions) => {
 							});
 							userId = newUser.id;
 							if (!userId) {
-								throw ctx.redirect(`${toRedirectTo}?error=USER_NOT_CREATED`);
+								throw ctx.redirect(
+									`${toRedirectTo}?error=failed_to_create_user`,
+								);
 							}
 						} else {
-							throw ctx.redirect(`${toRedirectTo}?error=USER_NOT_FOUND`);
+							throw ctx.redirect(`${toRedirectTo}?error=failed_to_create_user`);
 						}
 					}
 					const session = await ctx.context.internalAdapter.createSession(
@@ -216,7 +219,9 @@ export const magicLink = (options: MagicLinkOptions) => {
 						ctx.headers,
 					);
 					if (!session) {
-						throw ctx.redirect(`${toRedirectTo}?error=SESSION_NOT_CREATED`);
+						throw ctx.redirect(
+							`${toRedirectTo}?error=failed_to_create_session`,
+						);
 					}
 					await setSessionCookie(ctx, {
 						session,
diff --git a/packages/better-auth/src/plugins/multi-session/index.ts b/packages/better-auth/src/plugins/multi-session/index.ts
index 8d9d5f7d00..5cdb5a5630 100644
--- a/packages/better-auth/src/plugins/multi-session/index.ts
+++ b/packages/better-auth/src/plugins/multi-session/index.ts
@@ -30,6 +30,10 @@ export const multiSession = (options?: MultiSessionConfig) => {
 
 	const isMultiSessionCookie = (key: string) => key.includes("_multi-");
 
+	const ERROR_CODES = {
+		INVALID_SESSION_TOKEN: "Invalid session token",
+	} as const;
+
 	return {
 		id: "multi-session",
 		endpoints: {
@@ -109,7 +113,7 @@ export const multiSession = (options?: MultiSessionConfig) => {
 					);
 					if (!sessionCookie) {
 						throw new APIError("UNAUTHORIZED", {
-							message: "Invalid session token",
+							message: ERROR_CODES.INVALID_SESSION_TOKEN,
 						});
 					}
 					const session =
@@ -120,7 +124,7 @@ export const multiSession = (options?: MultiSessionConfig) => {
 							maxAge: 0,
 						});
 						throw new APIError("UNAUTHORIZED", {
-							message: "Invalid session token",
+							message: ERROR_CODES.INVALID_SESSION_TOKEN,
 						});
 					}
 					await setSessionCookie(ctx, session);
@@ -170,7 +174,7 @@ export const multiSession = (options?: MultiSessionConfig) => {
 					);
 					if (!sessionCookie) {
 						throw new APIError("UNAUTHORIZED", {
-							message: "Invalid session token",
+							message: ERROR_CODES.INVALID_SESSION_TOKEN,
 						});
 					}
 
@@ -284,5 +288,6 @@ export const multiSession = (options?: MultiSessionConfig) => {
 				},
 			],
 		},
+		$ERROR_CODES: ERROR_CODES,
 	} satisfies BetterAuthPlugin;
 };
diff --git a/packages/better-auth/src/plugins/organization/error-codes.ts b/packages/better-auth/src/plugins/organization/error-codes.ts
new file mode 100644
index 0000000000..a5c832e34d
--- /dev/null
+++ b/packages/better-auth/src/plugins/organization/error-codes.ts
@@ -0,0 +1,34 @@
+export const ORGANIZATION_ERROR_CODES = {
+	YOU_ARE_NOT_ALLOWED_TO_CREATE_A_NEW_ORGANIZATION:
+		"You are not allowed to create a new organization",
+	YOU_HAVE_REACHED_THE_MAXIMUM_NUMBER_OF_ORGANIZATIONS:
+		"You have reached the maximum number of organizations",
+	ORGANIZATION_ALREADY_EXISTS: "Organization already exists",
+	ORGANIZATION_NOT_FOUND: "Organization not found",
+	USER_IS_NOT_A_MEMBER_OF_THE_ORGANIZATION:
+		"User is not a member of the organization",
+	YOU_ARE_NOT_ALLOWED_TO_UPDATE_THIS_ORGANIZATION:
+		"You are not allowed to update this organization",
+	YOU_ARE_NOT_ALLOWED_TO_DELETE_THIS_ORGANIZATION:
+		"You are not allowed to delete this organization",
+	NO_ACTIVE_ORGANIZATION: "No active organization",
+	USER_IS_ALREADY_A_MEMBER_OF_THIS_ORGANIZATION:
+		"User is already a member of this organization",
+	MEMBER_NOT_FOUND: "Member not found",
+	ROLE_NOT_FOUND: "Role not found",
+	YOU_CANNOT_LEAVE_THE_ORGANIZATION_AS_THE_ONLY_OWNER:
+		"You cannot leave the organization as the only owner",
+	YOU_ARE_NOT_ALLOWED_TO_DELETE_THIS_MEMBER:
+		"You are not allowed to delete this member",
+	YOU_ARE_NOT_ALLOWED_TO_INVITE_USERS_TO_THIS_ORGANIZATION:
+		"You are not allowed to invite users to this organization",
+	USER_IS_ALREADY_INVITED_TO_THIS_ORGANIZATION:
+		"User is already invited to this organization",
+	INVITATION_NOT_FOUND: "Invitation not found",
+	YOU_ARE_NOT_THE_RECIPIENT_OF_THE_INVITATION:
+		"You are not the recipient of the invitation",
+	YOU_ARE_NOT_ALLOWED_TO_CANCEL_THIS_INVITATION:
+		"You are not allowed to cancel this invitation",
+	INVITER_IS_NO_LONGER_A_MEMBER_OF_THE_ORGANIZATION:
+		"Inviter is no longer a member of the organization",
+} as const;
diff --git a/packages/better-auth/src/plugins/organization/organization.ts b/packages/better-auth/src/plugins/organization/organization.ts
index 82d4a5e322..c73e5a1757 100644
--- a/packages/better-auth/src/plugins/organization/organization.ts
+++ b/packages/better-auth/src/plugins/organization/organization.ts
@@ -44,6 +44,7 @@ import {
 } from "./routes/crud-org";
 import type { Invitation, Member, Organization } from "./schema";
 import type { Prettify } from "../../types/helper";
+import { ORGANIZATION_ERROR_CODES } from "./error-codes";
 
 export interface OrganizationOptions {
 	/**
@@ -308,7 +309,7 @@ export const organization = <O extends OrganizationOptions>(options?: O) => {
 				async (ctx) => {
 					if (!ctx.context.session.session.activeOrganizationId) {
 						throw new APIError("BAD_REQUEST", {
-							message: "No active organization",
+							message: ORGANIZATION_ERROR_CODES.NO_ACTIVE_ORGANIZATION,
 						});
 					}
 					const adapter = getOrgAdapter(ctx.context);
@@ -319,7 +320,8 @@ export const organization = <O extends OrganizationOptions>(options?: O) => {
 					});
 					if (!member) {
 						throw new APIError("UNAUTHORIZED", {
-							message: "You are not a member of this organization",
+							message:
+								ORGANIZATION_ERROR_CODES.USER_IS_NOT_A_MEMBER_OF_THE_ORGANIZATION,
 						});
 					}
 					const role = roles[member.role as keyof typeof roles];
@@ -481,5 +483,6 @@ export const organization = <O extends OrganizationOptions>(options?: O) => {
 				}
 			>,
 		},
+		$ERROR_CODES: ORGANIZATION_ERROR_CODES,
 	} satisfies BetterAuthPlugin;
 };
diff --git a/packages/better-auth/src/plugins/organization/routes/crud-invites.ts b/packages/better-auth/src/plugins/organization/routes/crud-invites.ts
index e557fa5a8a..482a864385 100644
--- a/packages/better-auth/src/plugins/organization/routes/crud-invites.ts
+++ b/packages/better-auth/src/plugins/organization/routes/crud-invites.ts
@@ -6,6 +6,7 @@ import { orgMiddleware, orgSessionMiddleware } from "../call";
 import { type InferRolesFromOption } from "../schema";
 import { APIError } from "better-call";
 import type { OrganizationOptions } from "../organization";
+import { ORGANIZATION_ERROR_CODES } from "../error-codes";
 
 export const createInvitation = <O extends OrganizationOptions | undefined>(
 	option: O,
@@ -99,7 +100,7 @@ export const createInvitation = <O extends OrganizationOptions | undefined>(
 				ctx.body.organizationId || session.session.activeOrganizationId;
 			if (!organizationId) {
 				throw new APIError("BAD_REQUEST", {
-					message: "Organization not found",
+					message: ORGANIZATION_ERROR_CODES.ORGANIZATION_NOT_FOUND,
 				});
 			}
 			const adapter = getOrgAdapter(ctx.context, ctx.context.orgOptions);
@@ -109,13 +110,13 @@ export const createInvitation = <O extends OrganizationOptions | undefined>(
 			});
 			if (!member) {
 				throw new APIError("BAD_REQUEST", {
-					message: "Member not found!",
+					message: ORGANIZATION_ERROR_CODES.MEMBER_NOT_FOUND,
 				});
 			}
 			const role = ctx.context.roles[member.role];
 			if (!role) {
 				throw new APIError("BAD_REQUEST", {
-					message: "Role not found!",
+					message: ORGANIZATION_ERROR_CODES.ROLE_NOT_FOUND,
 				});
 			}
 			const canInvite = role.authorize({
@@ -123,7 +124,8 @@ export const createInvitation = <O extends OrganizationOptions | undefined>(
 			});
 			if (canInvite.error) {
 				throw new APIError("FORBIDDEN", {
-					message: "You are not allowed to invite members",
+					message:
+						ORGANIZATION_ERROR_CODES.YOU_ARE_NOT_ALLOWED_TO_INVITE_USERS_TO_THIS_ORGANIZATION,
 				});
 			}
 			const alreadyMember = await adapter.findMemberByEmail({
@@ -132,7 +134,8 @@ export const createInvitation = <O extends OrganizationOptions | undefined>(
 			});
 			if (alreadyMember) {
 				throw new APIError("BAD_REQUEST", {
-					message: "User is already a member of this organization",
+					message:
+						ORGANIZATION_ERROR_CODES.USER_IS_ALREADY_A_MEMBER_OF_THIS_ORGANIZATION,
 				});
 			}
 			const alreadyInvited = await adapter.findPendingInvitation({
@@ -141,7 +144,8 @@ export const createInvitation = <O extends OrganizationOptions | undefined>(
 			});
 			if (alreadyInvited.length && !ctx.body.resend) {
 				throw new APIError("BAD_REQUEST", {
-					message: "User is already invited to this organization",
+					message:
+						ORGANIZATION_ERROR_CODES.USER_IS_ALREADY_INVITED_TO_THIS_ORGANIZATION,
 				});
 			}
 			const invitation = await adapter.createInvitation({
@@ -157,7 +161,7 @@ export const createInvitation = <O extends OrganizationOptions | undefined>(
 
 			if (!organization) {
 				throw new APIError("BAD_REQUEST", {
-					message: "Organization not found",
+					message: ORGANIZATION_ERROR_CODES.ORGANIZATION_NOT_FOUND,
 				});
 			}
 
@@ -224,12 +228,13 @@ export const acceptInvitation = createAuthEndpoint(
 			invitation.status !== "pending"
 		) {
 			throw new APIError("BAD_REQUEST", {
-				message: "Invitation not found!",
+				message: ORGANIZATION_ERROR_CODES.INVITATION_NOT_FOUND,
 			});
 		}
 		if (invitation.email !== session.user.email) {
 			throw new APIError("FORBIDDEN", {
-				message: "You are not the recipient of the invitation",
+				message:
+					ORGANIZATION_ERROR_CODES.YOU_ARE_NOT_THE_RECIPIENT_OF_THE_INVITATION,
 			});
 		}
 		const acceptedI = await adapter.updateInvitation({
@@ -250,7 +255,7 @@ export const acceptInvitation = createAuthEndpoint(
 			return ctx.json(null, {
 				status: 400,
 				body: {
-					message: "Invitation not found!",
+					message: ORGANIZATION_ERROR_CODES.INVITATION_NOT_FOUND,
 				},
 			});
 		}
@@ -311,7 +316,8 @@ export const rejectInvitation = createAuthEndpoint(
 		}
 		if (invitation.email !== session.user.email) {
 			throw new APIError("FORBIDDEN", {
-				message: "You are not the recipient of the invitation",
+				message:
+					ORGANIZATION_ERROR_CODES.YOU_ARE_NOT_THE_RECIPIENT_OF_THE_INVITATION,
 			});
 		}
 		const rejectedI = await adapter.updateInvitation({
@@ -362,7 +368,7 @@ export const cancelInvitation = createAuthEndpoint(
 		const invitation = await adapter.findInvitationById(ctx.body.invitationId);
 		if (!invitation) {
 			throw new APIError("BAD_REQUEST", {
-				message: "Invitation not found!",
+				message: ORGANIZATION_ERROR_CODES.INVITATION_NOT_FOUND,
 			});
 		}
 		const member = await adapter.findMemberByOrgId({
@@ -371,7 +377,7 @@ export const cancelInvitation = createAuthEndpoint(
 		});
 		if (!member) {
 			throw new APIError("BAD_REQUEST", {
-				message: "Member not found!",
+				message: ORGANIZATION_ERROR_CODES.MEMBER_NOT_FOUND,
 			});
 		}
 		const canCancel = ctx.context.roles[member.role].authorize({
@@ -379,7 +385,8 @@ export const cancelInvitation = createAuthEndpoint(
 		});
 		if (canCancel.error) {
 			throw new APIError("FORBIDDEN", {
-				message: "You are not allowed to cancel this invitation",
+				message:
+					ORGANIZATION_ERROR_CODES.YOU_ARE_NOT_ALLOWED_TO_CANCEL_THIS_INVITATION,
 			});
 		}
 		const canceledI = await adapter.updateInvitation({
@@ -483,7 +490,8 @@ export const getInvitation = createAuthEndpoint(
 		}
 		if (invitation.email !== session.user.email) {
 			throw new APIError("FORBIDDEN", {
-				message: "You are not the recipient of the invitation",
+				message:
+					ORGANIZATION_ERROR_CODES.YOU_ARE_NOT_THE_RECIPIENT_OF_THE_INVITATION,
 			});
 		}
 		const organization = await adapter.findOrganizationById(
@@ -491,7 +499,7 @@ export const getInvitation = createAuthEndpoint(
 		);
 		if (!organization) {
 			throw new APIError("BAD_REQUEST", {
-				message: "Organization not found",
+				message: ORGANIZATION_ERROR_CODES.ORGANIZATION_NOT_FOUND,
 			});
 		}
 		const member = await adapter.findMemberByOrgId({
@@ -500,7 +508,8 @@ export const getInvitation = createAuthEndpoint(
 		});
 		if (!member) {
 			throw new APIError("BAD_REQUEST", {
-				message: "Inviter is no longer a member of the organization",
+				message:
+					ORGANIZATION_ERROR_CODES.INVITER_IS_NO_LONGER_A_MEMBER_OF_THE_ORGANIZATION,
 			});
 		}
 
diff --git a/packages/better-auth/src/plugins/organization/routes/crud-members.ts b/packages/better-auth/src/plugins/organization/routes/crud-members.ts
index f039e69691..8e533ec078 100644
--- a/packages/better-auth/src/plugins/organization/routes/crud-members.ts
+++ b/packages/better-auth/src/plugins/organization/routes/crud-members.ts
@@ -8,6 +8,8 @@ import type { User } from "../../../db/schema";
 import { generateId } from "../../../utils";
 import type { OrganizationOptions } from "../organization";
 import { getSessionFromCtx } from "../../../api";
+import { ORGANIZATION_ERROR_CODES } from "../error-codes";
+import { BASE_ERROR_CODES } from "../../../error/codes";
 
 export const addMember = <O extends OrganizationOptions>() =>
 	createAuthEndpoint(
@@ -38,7 +40,7 @@ export const addMember = <O extends OrganizationOptions>() =>
 				return ctx.json(null, {
 					status: 400,
 					body: {
-						message: "No active organization found!",
+						message: ORGANIZATION_ERROR_CODES.NO_ACTIVE_ORGANIZATION,
 					},
 				});
 			}
@@ -51,7 +53,7 @@ export const addMember = <O extends OrganizationOptions>() =>
 
 			if (!user) {
 				throw new APIError("BAD_REQUEST", {
-					message: "User not found!",
+					message: BASE_ERROR_CODES.USER_NOT_FOUND,
 				});
 			}
 
@@ -61,7 +63,8 @@ export const addMember = <O extends OrganizationOptions>() =>
 			});
 			if (alreadyMember) {
 				throw new APIError("BAD_REQUEST", {
-					message: "User is already a member of this organization",
+					message:
+						ORGANIZATION_ERROR_CODES.USER_IS_ALREADY_A_MEMBER_OF_THIS_ORGANIZATION,
 				});
 			}
 
@@ -143,7 +146,7 @@ export const removeMember = createAuthEndpoint(
 			return ctx.json(null, {
 				status: 400,
 				body: {
-					message: "No active organization found!",
+					message: ORGANIZATION_ERROR_CODES.NO_ACTIVE_ORGANIZATION,
 				},
 			});
 		}
@@ -154,13 +157,13 @@ export const removeMember = createAuthEndpoint(
 		});
 		if (!member) {
 			throw new APIError("BAD_REQUEST", {
-				message: "Member not found!",
+				message: ORGANIZATION_ERROR_CODES.MEMBER_NOT_FOUND,
 			});
 		}
 		const role = ctx.context.roles[member.role];
 		if (!role) {
 			throw new APIError("BAD_REQUEST", {
-				message: "Role not found!",
+				message: ORGANIZATION_ERROR_CODES.ROLE_NOT_FOUND,
 			});
 		}
 		const isLeaving =
@@ -171,7 +174,8 @@ export const removeMember = createAuthEndpoint(
 			member.role === (ctx.context.orgOptions?.creatorRole || "owner");
 		if (isOwnerLeaving) {
 			throw new APIError("BAD_REQUEST", {
-				message: "You cannot leave the organization as the owner",
+				message:
+					ORGANIZATION_ERROR_CODES.YOU_CANNOT_LEAVE_THE_ORGANIZATION_AS_THE_ONLY_OWNER,
 			});
 		}
 
@@ -182,7 +186,8 @@ export const removeMember = createAuthEndpoint(
 			}).success;
 		if (!canDeleteMember) {
 			throw new APIError("UNAUTHORIZED", {
-				message: "You are not allowed to delete this member",
+				message:
+					ORGANIZATION_ERROR_CODES.YOU_ARE_NOT_ALLOWED_TO_DELETE_THIS_MEMBER,
 			});
 		}
 		let existing: Member | null = null;
@@ -196,7 +201,7 @@ export const removeMember = createAuthEndpoint(
 		}
 		if (existing?.organizationId !== organizationId) {
 			throw new APIError("BAD_REQUEST", {
-				message: "Member not found!",
+				message: ORGANIZATION_ERROR_CODES.MEMBER_NOT_FOUND,
 			});
 		}
 		await adapter.deleteMember(existing.id);
@@ -273,7 +278,7 @@ export const updateMemberRole = <O extends OrganizationOptions>(option: O) =>
 				return ctx.json(null, {
 					status: 400,
 					body: {
-						message: "No active organization found!",
+						message: ORGANIZATION_ERROR_CODES.NO_ACTIVE_ORGANIZATION,
 					},
 				});
 			}
@@ -286,7 +291,7 @@ export const updateMemberRole = <O extends OrganizationOptions>(option: O) =>
 				return ctx.json(null, {
 					status: 400,
 					body: {
-						message: "Member not found!",
+						message: ORGANIZATION_ERROR_CODES.MEMBER_NOT_FOUND,
 					},
 				});
 			}
@@ -295,7 +300,7 @@ export const updateMemberRole = <O extends OrganizationOptions>(option: O) =>
 				return ctx.json(null, {
 					status: 400,
 					body: {
-						message: "Role not found!",
+						message: ORGANIZATION_ERROR_CODES.ROLE_NOT_FOUND,
 					},
 				});
 			}
@@ -325,7 +330,7 @@ export const updateMemberRole = <O extends OrganizationOptions>(option: O) =>
 				return ctx.json(null, {
 					status: 400,
 					body: {
-						message: "Member not found!",
+						message: ORGANIZATION_ERROR_CODES.MEMBER_NOT_FOUND,
 					},
 				});
 			}
@@ -378,7 +383,7 @@ export const getActiveMember = createAuthEndpoint(
 			return ctx.json(null, {
 				status: 400,
 				body: {
-					message: "No active organization found!",
+					message: ORGANIZATION_ERROR_CODES.NO_ACTIVE_ORGANIZATION,
 				},
 			});
 		}
@@ -391,7 +396,7 @@ export const getActiveMember = createAuthEndpoint(
 			return ctx.json(null, {
 				status: 400,
 				body: {
-					message: "Member not found!",
+					message: ORGANIZATION_ERROR_CODES.MEMBER_NOT_FOUND,
 				},
 			});
 		}
diff --git a/packages/better-auth/src/plugins/organization/routes/crud-org.ts b/packages/better-auth/src/plugins/organization/routes/crud-org.ts
index d6c97db0a0..8c4ca61ddc 100644
--- a/packages/better-auth/src/plugins/organization/routes/crud-org.ts
+++ b/packages/better-auth/src/plugins/organization/routes/crud-org.ts
@@ -5,6 +5,7 @@ import { getOrgAdapter } from "../adapter";
 import { orgMiddleware, orgSessionMiddleware } from "../call";
 import { APIError } from "better-call";
 import { setSessionCookie } from "../../../cookies";
+import { ORGANIZATION_ERROR_CODES } from "../error-codes";
 import { getSessionFromCtx } from "../../../api";
 
 export const createOrganization = createAuthEndpoint(
@@ -83,7 +84,8 @@ export const createOrganization = createAuthEndpoint(
 
 		if (!canCreateOrg) {
 			throw new APIError("FORBIDDEN", {
-				message: "You are not allowed to create an organization",
+				message:
+					ORGANIZATION_ERROR_CODES.YOU_ARE_NOT_ALLOWED_TO_CREATE_A_NEW_ORGANIZATION,
 			});
 		}
 		const adapter = getOrgAdapter(ctx.context, options);
@@ -98,7 +100,8 @@ export const createOrganization = createAuthEndpoint(
 
 		if (hasReachedOrgLimit) {
 			throw new APIError("FORBIDDEN", {
-				message: "You have reached the organization limit",
+				message:
+					ORGANIZATION_ERROR_CODES.YOU_HAVE_REACHED_THE_MAXIMUM_NUMBER_OF_ORGANIZATIONS,
 			});
 		}
 
@@ -107,7 +110,7 @@ export const createOrganization = createAuthEndpoint(
 		);
 		if (existingOrganization) {
 			throw new APIError("BAD_REQUEST", {
-				message: "Organization with this slug already exists",
+				message: ORGANIZATION_ERROR_CODES.ORGANIZATION_ALREADY_EXISTS,
 			});
 		}
 		const organization = await adapter.createOrganization({
@@ -197,7 +200,7 @@ export const updateOrganization = createAuthEndpoint(
 			return ctx.json(null, {
 				status: 400,
 				body: {
-					message: "Organization id not found!",
+					message: ORGANIZATION_ERROR_CODES.ORGANIZATION_NOT_FOUND,
 				},
 			});
 		}
@@ -210,7 +213,8 @@ export const updateOrganization = createAuthEndpoint(
 			return ctx.json(null, {
 				status: 400,
 				body: {
-					message: "User is not a member of this organization!",
+					message:
+						ORGANIZATION_ERROR_CODES.USER_IS_NOT_A_MEMBER_OF_THE_ORGANIZATION,
 				},
 			});
 		}
@@ -229,7 +233,8 @@ export const updateOrganization = createAuthEndpoint(
 		if (canUpdateOrg.error) {
 			return ctx.json(null, {
 				body: {
-					message: "You are not allowed to update this organization",
+					message:
+						ORGANIZATION_ERROR_CODES.YOU_ARE_NOT_ALLOWED_TO_UPDATE_THIS_ORGANIZATION,
 				},
 				status: 403,
 			});
@@ -284,7 +289,7 @@ export const deleteOrganization = createAuthEndpoint(
 			return ctx.json(null, {
 				status: 400,
 				body: {
-					message: "Organization id not found!",
+					message: ORGANIZATION_ERROR_CODES.ORGANIZATION_NOT_FOUND,
 				},
 			});
 		}
@@ -297,7 +302,8 @@ export const deleteOrganization = createAuthEndpoint(
 			return ctx.json(null, {
 				status: 400,
 				body: {
-					message: "User is not a member of this organization!",
+					message:
+						ORGANIZATION_ERROR_CODES.USER_IS_NOT_A_MEMBER_OF_THE_ORGANIZATION,
 				},
 			});
 		}
@@ -315,7 +321,8 @@ export const deleteOrganization = createAuthEndpoint(
 		});
 		if (canDeleteOrg.error) {
 			throw new APIError("FORBIDDEN", {
-				message: "You are not allowed to delete this organization",
+				message:
+					ORGANIZATION_ERROR_CODES.YOU_ARE_NOT_ALLOWED_TO_DELETE_THIS_ORGANIZATION,
 			});
 		}
 		if (organizationId === session.session.activeOrganizationId) {
@@ -387,7 +394,7 @@ export const getFullOrganization = createAuthEndpoint(
 		});
 		if (!organization) {
 			throw new APIError("BAD_REQUEST", {
-				message: "Organization not found",
+				message: ORGANIZATION_ERROR_CODES.ORGANIZATION_NOT_FOUND,
 			});
 		}
 		return ctx.json(organization);
@@ -470,7 +477,8 @@ export const setActiveOrganization = createAuthEndpoint(
 		if (!isMember) {
 			await adapter.setActiveOrganization(session.session.token, null);
 			throw new APIError("FORBIDDEN", {
-				message: "You are not a member of this organization",
+				message:
+					ORGANIZATION_ERROR_CODES.USER_IS_NOT_A_MEMBER_OF_THE_ORGANIZATION,
 			});
 		}
 		const updatedSession = await adapter.setActiveOrganization(
diff --git a/packages/better-auth/src/plugins/passkey/index.ts b/packages/better-auth/src/plugins/passkey/index.ts
index 1d24e95704..55b27a6719 100644
--- a/packages/better-auth/src/plugins/passkey/index.ts
+++ b/packages/better-auth/src/plugins/passkey/index.ts
@@ -107,6 +107,17 @@ export const passkey = (options?: PasskeyOptions) => {
 	const maxAgeInSeconds = Math.floor(
 		(expirationTime.getTime() - currentTime.getTime()) / 1000,
 	);
+
+	const ERROR_CODES = {
+		CHALLENGE_NOT_FOUND: "Challenge not found",
+		YOU_ARE_NOT_ALLOWED_TO_REGISTER_THIS_PASSKEY:
+			"You are not allowed to register this passkey",
+		FAILED_TO_VERIFY_REGISTRATION: "Failed to verify registration",
+		PASSKEY_NOT_FOUND: "Passkey not found",
+		AUTHENTICATION_FAILED: "Authentication failed",
+		UNABLE_TO_CREATE_SESSION: "Unable to create session",
+		FAILED_TO_UPDATE_PASSKEY: "Failed to update passkey",
+	} as const;
 	return {
 		id: "passkey",
 		endpoints: {
@@ -493,7 +504,7 @@ export const passkey = (options?: PasskeyOptions) => {
 					);
 					if (!challengeId) {
 						throw new APIError("BAD_REQUEST", {
-							message: "Challenge not found",
+							message: ERROR_CODES.CHALLENGE_NOT_FOUND,
 						});
 					}
 
@@ -512,7 +523,7 @@ export const passkey = (options?: PasskeyOptions) => {
 
 					if (userData.id !== ctx.context.session.user.id) {
 						throw new APIError("UNAUTHORIZED", {
-							message: "You are not authorized to register this passkey",
+							message: ERROR_CODES.YOU_ARE_NOT_ALLOWED_TO_REGISTER_THIS_PASSKEY,
 						});
 					}
 
@@ -559,7 +570,7 @@ export const passkey = (options?: PasskeyOptions) => {
 					} catch (e) {
 						console.log(e);
 						throw new APIError("INTERNAL_SERVER_ERROR", {
-							message: "Failed to verify registration",
+							message: ERROR_CODES.FAILED_TO_VERIFY_REGISTRATION,
 						});
 					}
 				},
@@ -611,7 +622,7 @@ export const passkey = (options?: PasskeyOptions) => {
 					);
 					if (!challengeId) {
 						throw new APIError("BAD_REQUEST", {
-							message: "Challenge not found",
+							message: ERROR_CODES.CHALLENGE_NOT_FOUND,
 						});
 					}
 
@@ -621,7 +632,7 @@ export const passkey = (options?: PasskeyOptions) => {
 						);
 					if (!data) {
 						throw new APIError("BAD_REQUEST", {
-							message: "Challenge not found",
+							message: ERROR_CODES.CHALLENGE_NOT_FOUND,
 						});
 					}
 					const { expectedChallenge } = JSON.parse(
@@ -638,7 +649,7 @@ export const passkey = (options?: PasskeyOptions) => {
 					});
 					if (!passkey) {
 						throw new APIError("UNAUTHORIZED", {
-							message: "Passkey not found",
+							message: ERROR_CODES.PASSKEY_NOT_FOUND,
 						});
 					}
 					try {
@@ -662,7 +673,7 @@ export const passkey = (options?: PasskeyOptions) => {
 						const { verified } = verification;
 						if (!verified)
 							throw new APIError("UNAUTHORIZED", {
-								message: "Authentication failed",
+								message: ERROR_CODES.AUTHENTICATION_FAILED,
 							});
 
 						await ctx.context.adapter.update<Passkey>({
@@ -683,7 +694,7 @@ export const passkey = (options?: PasskeyOptions) => {
 						);
 						if (!s) {
 							throw new APIError("INTERNAL_SERVER_ERROR", {
-								message: "Unable to create session",
+								message: ERROR_CODES.UNABLE_TO_CREATE_SESSION,
 							});
 						}
 						const user = await ctx.context.internalAdapter.findUserById(
@@ -709,7 +720,7 @@ export const passkey = (options?: PasskeyOptions) => {
 					} catch (e) {
 						ctx.context.logger.error("Failed to verify authentication", e);
 						throw new APIError("BAD_REQUEST", {
-							message: "Failed to verify authentication",
+							message: ERROR_CODES.AUTHENTICATION_FAILED,
 						});
 					}
 				},
@@ -777,13 +788,13 @@ export const passkey = (options?: PasskeyOptions) => {
 
 					if (!passkey) {
 						throw new APIError("NOT_FOUND", {
-							message: "Passkey not found",
+							message: ERROR_CODES.PASSKEY_NOT_FOUND,
 						});
 					}
 
 					if (passkey.userId !== ctx.context.session.user.id) {
 						throw new APIError("UNAUTHORIZED", {
-							message: "You are not authorized to update this passkey",
+							message: ERROR_CODES.YOU_ARE_NOT_ALLOWED_TO_REGISTER_THIS_PASSKEY,
 						});
 					}
 
@@ -802,7 +813,7 @@ export const passkey = (options?: PasskeyOptions) => {
 
 					if (!updatedPasskey) {
 						throw new APIError("INTERNAL_SERVER_ERROR", {
-							message: "Failed to update passkey",
+							message: ERROR_CODES.FAILED_TO_UPDATE_PASSKEY,
 						});
 					}
 					return ctx.json(
@@ -817,6 +828,7 @@ export const passkey = (options?: PasskeyOptions) => {
 			),
 		},
 		schema: mergeSchema(schema, options?.schema),
+		$ERROR_CODES: ERROR_CODES,
 	} satisfies BetterAuthPlugin;
 };
 
diff --git a/packages/better-auth/src/plugins/phone-number/index.ts b/packages/better-auth/src/plugins/phone-number/index.ts
index 1603c4aacf..413c4e909e 100644
--- a/packages/better-auth/src/plugins/phone-number/index.ts
+++ b/packages/better-auth/src/plugins/phone-number/index.ts
@@ -11,6 +11,7 @@ import { alphabet, generateRandomString } from "../../crypto/random";
 import { getSessionFromCtx } from "../../api";
 import { getDate } from "../../utils/date";
 import { setSessionCookie } from "../../cookies";
+import { BASE_ERROR_CODES } from "../../error/codes";
 
 export interface UserWithPhoneNumber extends User {
 	phoneNumber: string;
@@ -101,6 +102,13 @@ export const phoneNumber = (options?: {
 		code: "code",
 		createdAt: "createdAt",
 	};
+
+	const ERROR_CODES = {
+		INVALID_PHONE_NUMBER: "Invalid phone number",
+		INVALID_PHONE_NUMBER_OR_PASSWORD: "Invalid phone number or password",
+		UNEXPECTED_ERROR: "Unexpected error",
+		OTP_NOT_FOUND: "OTP not found",
+	} as const;
 	return {
 		id: "phone-number",
 		endpoints: {
@@ -160,7 +168,7 @@ export const phoneNumber = (options?: {
 						);
 						if (!isValidNumber) {
 							throw new APIError("BAD_REQUEST", {
-								message: "Invalid phone number!",
+								message: ERROR_CODES.INVALID_PHONE_NUMBER,
 							});
 						}
 					}
@@ -176,7 +184,7 @@ export const phoneNumber = (options?: {
 					});
 					if (!user) {
 						throw new APIError("UNAUTHORIZED", {
-							message: "Invalid phone number or password",
+							message: ERROR_CODES.INVALID_PHONE_NUMBER_OR_PASSWORD,
 						});
 					}
 					const accounts =
@@ -189,14 +197,14 @@ export const phoneNumber = (options?: {
 							phoneNumber,
 						});
 						throw new APIError("UNAUTHORIZED", {
-							message: "Invalid password or password",
+							message: ERROR_CODES.INVALID_PHONE_NUMBER_OR_PASSWORD,
 						});
 					}
 					const currentPassword = credentialAccount?.password;
 					if (!currentPassword) {
 						ctx.context.logger.error("Password not found", { phoneNumber });
 						throw new APIError("UNAUTHORIZED", {
-							message: "Unexpected error",
+							message: ERROR_CODES.UNEXPECTED_ERROR,
 						});
 					}
 					const validPassword = await ctx.context.password.verify({
@@ -206,7 +214,7 @@ export const phoneNumber = (options?: {
 					if (!validPassword) {
 						ctx.context.logger.error("Invalid password");
 						throw new APIError("UNAUTHORIZED", {
-							message: "Invalid email or password",
+							message: ERROR_CODES.INVALID_PHONE_NUMBER_OR_PASSWORD,
 						});
 					}
 					const session = await ctx.context.internalAdapter.createSession(
@@ -217,7 +225,7 @@ export const phoneNumber = (options?: {
 					if (!session) {
 						ctx.context.logger.error("Failed to create session");
 						throw new APIError("UNAUTHORIZED", {
-							message: "Failed to create session",
+							message: BASE_ERROR_CODES.FAILED_TO_CREATE_SESSION,
 						});
 					}
 
@@ -282,7 +290,7 @@ export const phoneNumber = (options?: {
 						);
 						if (!isValidNumber) {
 							throw new APIError("BAD_REQUEST", {
-								message: "Invalid phone number!",
+								message: ERROR_CODES.INVALID_PHONE_NUMBER,
 							});
 						}
 					}
@@ -391,7 +399,7 @@ export const phoneNumber = (options?: {
 							});
 						}
 						throw new APIError("BAD_REQUEST", {
-							message: "OTP not found",
+							message: ERROR_CODES.OTP_NOT_FOUND,
 						});
 					}
 					if (otp.value !== ctx.body.code) {
@@ -406,7 +414,7 @@ export const phoneNumber = (options?: {
 						const session = await getSessionFromCtx(ctx);
 						if (!session) {
 							throw new APIError("UNAUTHORIZED", {
-								message: "Session not found",
+								message: BASE_ERROR_CODES.USER_NOT_FOUND,
 							});
 						}
 						const user = await ctx.context.internalAdapter.updateUser(
@@ -454,7 +462,7 @@ export const phoneNumber = (options?: {
 							});
 							if (!user) {
 								throw new APIError("INTERNAL_SERVER_ERROR", {
-									message: "Failed to create user",
+									message: BASE_ERROR_CODES.FAILED_TO_CREATE_USER,
 								});
 							}
 						} else {
@@ -468,7 +476,7 @@ export const phoneNumber = (options?: {
 
 					if (!user) {
 						throw new APIError("INTERNAL_SERVER_ERROR", {
-							message: "Failed to update user",
+							message: BASE_ERROR_CODES.FAILED_TO_UPDATE_USER,
 						});
 					}
 
@@ -479,7 +487,7 @@ export const phoneNumber = (options?: {
 						);
 						if (!session) {
 							throw new APIError("INTERNAL_SERVER_ERROR", {
-								message: "Failed to create session",
+								message: BASE_ERROR_CODES.FAILED_TO_CREATE_SESSION,
 							});
 						}
 						await setSessionCookie(ctx, {
@@ -500,6 +508,7 @@ export const phoneNumber = (options?: {
 			),
 		},
 		schema: mergeSchema(schema, options?.schema),
+		$ERROR_CODES: ERROR_CODES,
 	} satisfies BetterAuthPlugin;
 };
 
diff --git a/packages/better-auth/src/plugins/two-factor/backup-codes/index.ts b/packages/better-auth/src/plugins/two-factor/backup-codes/index.ts
index aaa983ccd2..da464b4ab6 100644
--- a/packages/better-auth/src/plugins/two-factor/backup-codes/index.ts
+++ b/packages/better-auth/src/plugins/two-factor/backup-codes/index.ts
@@ -11,6 +11,7 @@ import type {
 } from "../types";
 import { APIError } from "better-call";
 import { setSessionCookie } from "../../../cookies";
+import { TWO_FACTOR_ERROR_CODES } from "../error-code";
 
 export interface BackupCodeOptions {
 	/**
@@ -121,7 +122,7 @@ export const backupCode2fa = (
 					});
 					if (!twoFactor) {
 						throw new APIError("BAD_REQUEST", {
-							message: "Backup codes aren't enabled",
+							message: TWO_FACTOR_ERROR_CODES.BACKUP_CODES_NOT_ENABLED,
 						});
 					}
 					const validate = await verifyBackupCode(
@@ -133,7 +134,7 @@ export const backupCode2fa = (
 					);
 					if (!validate.status) {
 						throw new APIError("UNAUTHORIZED", {
-							message: "Invalid backup code",
+							message: TWO_FACTOR_ERROR_CODES.INVALID_BACKUP_CODE,
 						});
 					}
 					const updatedBackupCodes = await symmetricEncrypt({
@@ -179,7 +180,7 @@ export const backupCode2fa = (
 					const user = ctx.context.session.user as UserWithTwoFactor;
 					if (!user.twoFactorEnabled) {
 						throw new APIError("BAD_REQUEST", {
-							message: "Two factor isn't enabled",
+							message: TWO_FACTOR_ERROR_CODES.TWO_FACTOR_NOT_ENABLED,
 						});
 					}
 					await ctx.context.password.checkPassword(user.id, ctx);
@@ -237,7 +238,7 @@ export const backupCode2fa = (
 					);
 					if (!backupCodes) {
 						throw new APIError("BAD_REQUEST", {
-							message: "Backup codes aren't enabled",
+							message: TWO_FACTOR_ERROR_CODES.BACKUP_CODES_NOT_ENABLED,
 						});
 					}
 					return ctx.json({
diff --git a/packages/better-auth/src/plugins/two-factor/error-code.ts b/packages/better-auth/src/plugins/two-factor/error-code.ts
new file mode 100644
index 0000000000..f32dda68fc
--- /dev/null
+++ b/packages/better-auth/src/plugins/two-factor/error-code.ts
@@ -0,0 +1,8 @@
+export const TWO_FACTOR_ERROR_CODES = {
+	OTP_NOT_ENABLED: "OTP not enabled",
+	OTP_HAS_EXPIRED: "OTP has expired",
+	TOTP_NOT_ENABLED: "TOTP not enabled",
+	TWO_FACTOR_NOT_ENABLED: "Two factor isn't enabled",
+	BACKUP_CODES_NOT_ENABLED: "Backup codes aren't enabled",
+	INVALID_BACKUP_CODE: "Invalid backup code",
+} as const;
diff --git a/packages/better-auth/src/plugins/two-factor/index.ts b/packages/better-auth/src/plugins/two-factor/index.ts
index dd6ad856b0..f666976f76 100644
--- a/packages/better-auth/src/plugins/two-factor/index.ts
+++ b/packages/better-auth/src/plugins/two-factor/index.ts
@@ -17,6 +17,7 @@ import { TimeSpan } from "oslo";
 import { deleteSessionCookie, setSessionCookie } from "../../cookies";
 import { getEndpointResponse } from "../../utils/plugin-helper";
 import { schema } from "./schema";
+import { BASE_ERROR_CODES } from "../../error/codes";
 
 export const twoFactor = (options?: TwoFactorOptions) => {
 	const opts = {
@@ -41,6 +42,7 @@ export const twoFactor = (options?: TwoFactorOptions) => {
 		},
 		opts.twoFactorTable,
 	);
+
 	return {
 		id: "two-factor",
 		endpoints: {
@@ -101,7 +103,7 @@ export const twoFactor = (options?: TwoFactorOptions) => {
 					});
 					if (!isPasswordValid) {
 						throw new APIError("BAD_REQUEST", {
-							message: "Invalid password",
+							message: BASE_ERROR_CODES.INVALID_PASSWORD,
 						});
 					}
 					const secret = generateRandomString(16, alphabet("a-z", "0-9", "-"));
diff --git a/packages/better-auth/src/plugins/two-factor/otp/index.ts b/packages/better-auth/src/plugins/two-factor/otp/index.ts
index 38ffcf548c..bfa7148ec0 100644
--- a/packages/better-auth/src/plugins/two-factor/otp/index.ts
+++ b/packages/better-auth/src/plugins/two-factor/otp/index.ts
@@ -9,6 +9,7 @@ import type {
 } from "../types";
 import { TimeSpan } from "oslo";
 import { alphabet, generateRandomString } from "../../../crypto";
+import { TWO_FACTOR_ERROR_CODES } from "../error-code";
 
 export interface OTPOptions {
 	/**
@@ -111,7 +112,7 @@ export const otp2fa = (options: OTPOptions, twoFactorTable: string) => {
 			});
 			if (!twoFactor) {
 				throw new APIError("BAD_REQUEST", {
-					message: "OTP isn't enabled",
+					message: TWO_FACTOR_ERROR_CODES.OTP_NOT_ENABLED,
 				});
 			}
 			const code = generateRandomString(opts.digits, alphabet("0-9"));
@@ -177,7 +178,7 @@ export const otp2fa = (options: OTPOptions, twoFactorTable: string) => {
 			});
 			if (!twoFactor) {
 				throw new APIError("BAD_REQUEST", {
-					message: "OTP isn't enabled",
+					message: TWO_FACTOR_ERROR_CODES.OTP_NOT_ENABLED,
 				});
 			}
 			const toCheckOtp =
@@ -186,7 +187,7 @@ export const otp2fa = (options: OTPOptions, twoFactorTable: string) => {
 				);
 			if (!toCheckOtp || toCheckOtp.expiresAt < new Date()) {
 				throw new APIError("BAD_REQUEST", {
-					message: "OTP has expired",
+					message: TWO_FACTOR_ERROR_CODES.OTP_HAS_EXPIRED,
 				});
 			}
 			if (toCheckOtp.value === ctx.body.code) {
diff --git a/packages/better-auth/src/plugins/two-factor/totp/index.ts b/packages/better-auth/src/plugins/two-factor/totp/index.ts
index 9435233ab9..d53590dfcc 100644
--- a/packages/better-auth/src/plugins/two-factor/totp/index.ts
+++ b/packages/better-auth/src/plugins/two-factor/totp/index.ts
@@ -13,6 +13,7 @@ import type {
 	UserWithTwoFactor,
 } from "../types";
 import { setSessionCookie } from "../../../cookies";
+import { TWO_FACTOR_ERROR_CODES } from "../error-code";
 
 export type TOTPOptions = {
 	/**
@@ -93,7 +94,7 @@ export const totp2fa = (options: TOTPOptions, twoFactorTable: string) => {
 			});
 			if (!twoFactor) {
 				throw new APIError("BAD_REQUEST", {
-					message: "totp isn't enabled",
+					message: TWO_FACTOR_ERROR_CODES.TOTP_NOT_ENABLED,
 				});
 			}
 			const totp = new TOTPController(opts);
@@ -157,7 +158,7 @@ export const totp2fa = (options: TOTPOptions, twoFactorTable: string) => {
 			});
 			if (!twoFactor || !user.twoFactorEnabled) {
 				throw new APIError("BAD_REQUEST", {
-					message: "totp isn't enabled",
+					message: TWO_FACTOR_ERROR_CODES.TOTP_NOT_ENABLED,
 				});
 			}
 			await ctx.context.password.checkPassword(user.id, ctx);
@@ -228,7 +229,7 @@ export const totp2fa = (options: TOTPOptions, twoFactorTable: string) => {
 
 			if (!twoFactor) {
 				throw new APIError("BAD_REQUEST", {
-					message: "totp isn't enabled",
+					message: TWO_FACTOR_ERROR_CODES.TOTP_NOT_ENABLED,
 				});
 			}
 			const totp = new TOTPController(opts);
diff --git a/packages/better-auth/src/plugins/username/index.ts b/packages/better-auth/src/plugins/username/index.ts
index d8669b3ecb..2f1e52aa8a 100644
--- a/packages/better-auth/src/plugins/username/index.ts
+++ b/packages/better-auth/src/plugins/username/index.ts
@@ -5,8 +5,15 @@ import { APIError } from "better-call";
 import type { Account, User } from "../../db/schema";
 import { setSessionCookie } from "../../cookies";
 import { sendVerificationEmailFn } from "../../api";
+import { BASE_ERROR_CODES } from "../../error/codes";
+import { TWO_FACTOR_ERROR_CODES } from "../two-factor/error-code";
 
 export const username = () => {
+	const ERROR_CODES = {
+		INVALID_USERNAME_OR_PASSWORD: "invalid username or password",
+		EMAIL_NOT_VERIFIED: "email not verified",
+		UNEXPECTED_ERROR: "unexpected error",
+	};
 	return {
 		id: "username",
 		endpoints: {
@@ -68,7 +75,7 @@ export const username = () => {
 						await ctx.context.password.hash(ctx.body.password);
 						ctx.context.logger.error("User not found", { username });
 						throw new APIError("UNAUTHORIZED", {
-							message: "Invalid username or password",
+							message: ERROR_CODES.INVALID_USERNAME_OR_PASSWORD,
 						});
 					}
 
@@ -78,7 +85,7 @@ export const username = () => {
 					) {
 						await sendVerificationEmailFn(ctx, user);
 						throw new APIError("UNAUTHORIZED", {
-							message: "Email not verified",
+							message: ERROR_CODES.INVALID_USERNAME_OR_PASSWORD,
 						});
 					}
 
@@ -97,14 +104,14 @@ export const username = () => {
 					});
 					if (!account) {
 						throw new APIError("UNAUTHORIZED", {
-							message: "Invalid username or password",
+							message: ERROR_CODES.INVALID_USERNAME_OR_PASSWORD,
 						});
 					}
 					const currentPassword = account?.password;
 					if (!currentPassword) {
 						ctx.context.logger.error("Password not found", { username });
 						throw new APIError("UNAUTHORIZED", {
-							message: "Unexpected error",
+							message: ERROR_CODES.INVALID_USERNAME_OR_PASSWORD,
 						});
 					}
 					const validPassword = await ctx.context.password.verify({
@@ -114,7 +121,7 @@ export const username = () => {
 					if (!validPassword) {
 						ctx.context.logger.error("Invalid password");
 						throw new APIError("UNAUTHORIZED", {
-							message: "Invalid username or password",
+							message: ERROR_CODES.INVALID_USERNAME_OR_PASSWORD,
 						});
 					}
 					const session = await ctx.context.internalAdapter.createSession(
@@ -126,7 +133,7 @@ export const username = () => {
 						return ctx.json(null, {
 							status: 500,
 							body: {
-								message: "Failed to create session",
+								message: BASE_ERROR_CODES.FAILED_TO_CREATE_SESSION,
 								status: 500,
 							},
 						});
@@ -155,5 +162,6 @@ export const username = () => {
 				},
 			},
 		},
+		$ERROR_CODES: TWO_FACTOR_ERROR_CODES,
 	} satisfies BetterAuthPlugin;
 };
diff --git a/packages/better-auth/src/types/plugins.ts b/packages/better-auth/src/types/plugins.ts
index 483efefce0..e6ec084670 100644
--- a/packages/better-auth/src/types/plugins.ts
+++ b/packages/better-auth/src/types/plugins.ts
@@ -3,7 +3,7 @@ import type { Migration } from "kysely";
 import type { AuthEndpoint } from "../api/call";
 import type { FieldAttribute } from "../db/field";
 import type { HookEndpointContext } from "./context";
-import type { DeepPartial, LiteralString } from "./helper";
+import type { DeepPartial, LiteralString, UnionToIntersection } from "./helper";
 import type { AuthContext, BetterAuthOptions } from ".";
 
 export type PluginSchema = {
@@ -137,6 +137,10 @@ export type BetterAuthPlugin = {
 		max: number;
 		pathMatcher: (path: string) => boolean;
 	}[];
+	/**
+	 * The error codes returned by the plugin
+	 */
+	$ERROR_CODES?: Record<string, string>;
 };
 
 export type InferOptionSchema<S extends PluginSchema> = S extends Record<
@@ -152,3 +156,14 @@ export type InferOptionSchema<S extends PluginSchema> = S extends Record<
 			};
 		}
 	: never;
+
+export type InferPluginErrorCodes<O extends BetterAuthOptions> =
+	O["plugins"] extends Array<infer P>
+		? UnionToIntersection<
+				P extends BetterAuthPlugin
+					? P["$ERROR_CODES"] extends Record<string, any>
+						? P["$ERROR_CODES"]
+						: {}
+					: {}
+			>
+		: {};