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issue: Uncaught (in promise) TypeErrors causes UI to freeze in multi-model chat when navigating message history #6761
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Originally created by @silentoplayz on GitHub (Oct 24, 2025).
Check Existing Issues
Installation Method
Docker
Open WebUI Version
v0.6.34
Ollama Version (if applicable)
v0.12.6
Operating System
Ubuntu 24.04.3 LTS
Browser (if applicable)
Mozilla Firefox Snap for Ubuntu - v144.0 (64-bit)
Confirmation
README.md.Expected Behavior
When navigating back to a previous message that I've sent in the chat history, the UI should remain stable and display the historical message content, even if the set of selected models has been changed. The application should not crash or throw any JavaScript errors.
Actual Behavior
Rather than being displayed the responses that the model(s) provided to my message, I am shown only my message in the chat and not the model's responses. The application gets caught in an exception that isn't being handled properly and the UI becomes unresponsive, forcing me to adjust the URL, followed by a page refresh to workaround the issue. The browser console shows an
Uncaught (in promise) TypeError: can't access property "messageIds", e[21][e[23]] is undefinederror originating from theMultiResponseMessages.sveltecomponent.Steps to Reproduce
Prerequisite: Ensure
Display Multi-model Responses in Tabsis toggled on in the user'sInterfacesettings. This is a vital setting that needs to be on for this bug to be reproducible at all.Start a new chat.
Select 3 different models in the model selector at the top of the chat page.

Send a query to all 3 models (e.g., "Tell me a fun fact about the Roman empire").

Wait for all models to finish generating a response.
Click the "Edit" pencil icon for the message you just sent and re-send the same message.

Once the models have finished generating again, remove ONE of the models selected from the model selector. I removed the bottom one here.

Click the back arrow (

<) on your message to navigate back to the initial set of responses sent to all 3 models.Observe that the page freezes and a

TypeErroris thrown in the browser console.Logs & Screenshots
Browser Console Error:
Screen recording of how to reproduce this issue:
https://github.com/user-attachments/assets/ac5f97fd-7b82-4e33-b2f9-7f89c1374a96
Agentic AI Analysis
The root cause of this bug is a state management issue in the
MultiResponseMessages.sveltecomponent.When a user sends a message to multiple models, the
parentMessage.modelsarray (a snapshot of the selected models at that time) is used to group the responses. The component'sinitHandlerfunction iterates over this historical array and uses the model's index (modelIdx) to build thegroupedMessageIdsandgroupedMessageIdsIdxobjects.The crash occurs when a user navigates back in the chat history after changing the currently selected models. The
initHandlerre-runs using the old list of models from the parent message, but the part of the component that renders the response tabs uses the new, currently selected models.This creates a state mismatch. When a model has been removed, the rendering logic attempts to access an index in the
groupedMessageIdsobject that was never populated (because the model isn't in the new list), leading to an attempt to access a property onundefined.File:
src/lib/components/chat/Messages/MultiResponseMessages.svelte@acomarcho commented on GitHub (Nov 1, 2025):
Can confirm that this happens in my device too, latest
dev. But an interesting thing is if you refresh the page and try to recreate it without sending new messages, it doesn't seem to crash, as in you can remove the models and navigate around the past chats/different tabs just fine.