Where does the bug appear (feature/product)?
Cursor IDE
Describe the Bug
Here is how my open chat was:
First Message:
Agent:
…
Second Message:
Agent…
Third message:
agent…
Now: the third mesage (With Claude 4.5 Sonnet), was ran, but failed due to this error: “Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools [internal]” (I copy pasted it to bug report that, because it still charged requests). So, I went to edit the prompt for the third message, to run it with GPT-5. All I did was change a few words, add a command–but then I got a popup for an update, and I was about to make a coffee–so clicked it, and left for a moment to let it restart. Come back, and the chat itself is reverted to how it was before I had even chatted at all (i ran the first message last night–seperate session that is). This was when I had an Agent Mode window open–I’ve never had issues updating in the middle of my work like this before, in the editor mode.
This just deleted HOURS of work–and was far more than 2 messages worth of progress deleted, because each of those were ran several times, and tuned until they worked–and it’s now deleted. Like 20 requests–> trash.
since release, Agent window has consistently been destroying my work in progress, something editor Window never does.
Steps to Reproduce
Update While Editing a previous message in Agent Window.
Maybe this needs to be done after an error occurs (i.e. it had prompted me to “resume”) specifically: Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools [internal];
Expected Behavior
It should have reopened the windows I had open, back in the same state it was in when I had clicked “Update Now”; The same Chat, same message, same state.
Operating System
Windows 10/11
Current Cursor Version (Menu → About Cursor → Copy)
Version: 1.7.25 (user setup)
VSCode Version: 1.99.3
Commit: 429604585b94ab2b96a4dabff4660f41d5b7fb80
Date: 2025-09-30T15:26:29.622Z
Electron: 34.5.8
Chromium: 132.0.6834.210
Node.js: 20.19.1
V8: 13.2.152.41-electron.0
OS: Windows_NT x64 10.0.26100
For AI issues: which model did you use?
Sonnet 4.5 Sonnet
For AI issues: add Request ID with privacy disabled
Cannot.
Additional Information
I’ve done exactly this update procedure consistently in the past, ever since having installed Cursor, without issue–updating while editing a message, normally, it’s always saved perfectly.
Also, this was my first attempt at using Agent Browser Mode–I had prompted it to use the Web Browser in the latest(3rd) message, perhaps this contributed to it?
Does this stop you from using Cursor
Sometimes - I can sometimes use Cursor