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[PR #21984] [CLOSED] fix: graceful error handling for malformed tool call arguments #49426

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opened 2026-04-30 01:44:10 -05:00 by GiteaMirror · 0 comments
GiteaMirror commented 2026-04-30 01:44:10 -05:00
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📋 Pull Request Information

Original PR: https://github.com/open-webui/open-webui/pull/21984
Author: @sxu75374
Created: 2/28/2026
Status: ❌ Closed

Base: dev ← Head: fix/graceful-malformed-tool-args

📝 Commits (10+)

📊 Changes

2 files changed (+138 additions, -3 deletions)

View changed files

➕ backend/open_webui/test/utils/test_tool_call_parsing.py (+130 -0)
📝 backend/open_webui/utils/middleware.py (+8 -3)

📄 Description

Summary

When an LLM produces truncated or malformed JSON in tool call arguments (e.g., during long tool calls that exceed token limits), the SSE stream crashes with an unhandled exception. This PR adds graceful error handling: on parse failure, tool execution is skipped and a descriptive error message is returned to the LLM, allowing it to retry or respond appropriately.

Changes

  • middleware.py: Add tool_args_parse_error flag when json.loads() fails on tool arguments. Guard tool execution behind this flag. On error, return a descriptive error message to the LLM instead of crashing.
  • test_tool_call_parsing.py: 11 unit tests covering malformed JSON (truncated, empty, null, non-dict), valid JSON, and edge cases.

Testing

  • ✅ Personally tested with intentionally truncated tool call JSON — stream continues, LLM receives error and retries
  • ✅ All 11 new unit tests pass
  • ✅ Existing tool call flows unaffected (normal JSON parsing path unchanged)

Contributor License Agreement

By submitting this pull request, I confirm that I have read and fully agree to the Contributor License Agreement (CLA), and I am providing my contributions under its terms.

Signed-off-by: sxu75374 imshuaixu@gmail.com

🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.

## 📋 Pull Request Information **Original PR:** https://github.com/open-webui/open-webui/pull/21984 **Author:** [@sxu75374](https://github.com/sxu75374) **Created:** 2/28/2026 **Status:** ❌ Closed **Base:** `dev` ← **Head:** `fix/graceful-malformed-tool-args` --- ### 📝 Commits (10+) - [`fe6783c`](https://github.com/open-webui/open-webui/commit/fe6783c16699911c7be17392596d579333fb110c) Merge pull request #19030 from open-webui/dev - [`fc05e0a`](https://github.com/open-webui/open-webui/commit/fc05e0a6c5d39da60b603b4d520f800d6e36f748) Merge pull request #19405 from open-webui/dev - [`e3faec6`](https://github.com/open-webui/open-webui/commit/e3faec62c58e3a83d89aa3df539feacefa125e0c) Merge pull request #19416 from open-webui/dev - [`9899293`](https://github.com/open-webui/open-webui/commit/9899293f050ad50ae12024cbebee7e018acd851e) Merge pull request #19448 from open-webui/dev - [`140605e`](https://github.com/open-webui/open-webui/commit/140605e660b8186a7d5c79fb3be6ffb147a2f498) Merge pull request #19462 from open-webui/dev - [`6f1486f`](https://github.com/open-webui/open-webui/commit/6f1486ffd0cb288d0e21f41845361924e0d742b3) Merge pull request #19466 from open-webui/dev - [`d95f533`](https://github.com/open-webui/open-webui/commit/d95f533214e3fe5beb5e41ec1f349940bc4c7043) Merge pull request #19729 from open-webui/dev - [`a727153`](https://github.com/open-webui/open-webui/commit/a7271532f8a38da46785afcaa7e65f9a45e7d753) 0.6.43 (#20093) - [`6adde20`](https://github.com/open-webui/open-webui/commit/6adde203cd292a9e3af9c64a2ae36b603fed096a) Merge pull request #20394 from open-webui/dev - [`f9b0534`](https://github.com/open-webui/open-webui/commit/f9b0534e0c442631d1cb7205169588b9b6204179) Merge pull request #20522 from open-webui/dev ### 📊 Changes **2 files changed** (+138 additions, -3 deletions) <details> <summary>View changed files</summary> ➕ `backend/open_webui/test/utils/test_tool_call_parsing.py` (+130 -0) 📝 `backend/open_webui/utils/middleware.py` (+8 -3) </details> ### 📄 Description ## Summary When an LLM produces truncated or malformed JSON in tool call arguments (e.g., during long tool calls that exceed token limits), the SSE stream crashes with an unhandled exception. This PR adds graceful error handling: on parse failure, tool execution is skipped and a descriptive error message is returned to the LLM, allowing it to retry or respond appropriately. ## Changes - **`middleware.py`**: Add `tool_args_parse_error` flag when `json.loads()` fails on tool arguments. Guard tool execution behind this flag. On error, return a descriptive error message to the LLM instead of crashing. - **`test_tool_call_parsing.py`**: 11 unit tests covering malformed JSON (truncated, empty, null, non-dict), valid JSON, and edge cases. ## Testing - ✅ Personally tested with intentionally truncated tool call JSON — stream continues, LLM receives error and retries - ✅ All 11 new unit tests pass - ✅ Existing tool call flows unaffected (normal JSON parsing path unchanged) ### Contributor License Agreement By submitting this pull request, I confirm that I have read and fully agree to the [Contributor License Agreement (CLA)](https://github.com/open-webui/open-webui/blob/main/CONTRIBUTOR_LICENSE_AGREEMENT), and I am providing my contributions under its terms. Signed-off-by: sxu75374 <imshuaixu@gmail.com> --- <sub>🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.</sub>
GiteaMirror added the pull-request label 2026-04-30 01:44:10 -05:00
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Reference: github-starred/open-webui#49426
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