I AM FACING THE SAME ISSUE CONTINUOUSLY.
Connection failed. If the problem persists, please check your internet connection or VPN
Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools [internal]
(Request ID: 8126a98f-1b4e-4dd7-8082-bbb374a8ecf7)
Same error:
Versione: 1.7.44 (user setup)
Commit: 1.99.3
Data: 9d178a4■■■89981b62546448bb32920a8219a5d0
Electron: 2025-10-10T15:43:37.500Z
ElectronBuildId: 34.5.8
Chromium: undefined
Node.js: 132.0.6834.210
V8: 20.19.1
Sistema operativo: 13.2.152.41-electron.0
Connection failed. If the problem persists, please check your internet connection or VPN
Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools [internal]
(Request ID: 64b501be-0a12-4983-99d7-c929eacb6267)
same issue. again and again since days.
Connection failed. If the problem persists, please check your internet connection or VPN
Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools [internal]
(Request ID: 1cb24f4e-7424-49aa-8df2-5aa3e00e8ee3)
Same error here for weeks, this is so frustrating, Cursor has become unusable….
Same issue here as well, please do something, get Claude-4.5 to look at it at least, it’ll probably figure it out atp
Background Agent (GitHub, Slack, Web, Linear)
This is the second major incident in less than a week.
After losing all my chat and Agent Mode history due to the previous bug (see: https://forum.cursor.com/t/conversation-history-invisible-after-cursor-update-to-1-7-44-data-intact-but-not-displayed/137133/2
),
Cursor is now throwing a serialization error every time I try to use Chat or Agent Mode.
Error message:
Request ID: 3ef56123-2a21-48a2-8d60-e751b6ae08fa
ConnectError: [internal] Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools
Multiple users are now reporting the same issue — this is not isolated.
It completely prevents the chat stream from functioning, even in new sessions with tools disabled.
Open Cursor IDE.
Start a new Chat or Agent session.
Type any prompt and send it.
The response fails immediately with the serialization error shown above.
The issue persists even after sign-out/in, reinstall, or clearing cache.
The chat or Agent Mode should initialize normally and stream a response.
Instead, the stream fails instantly with a serialization error and Cursor becomes unusable for any AI-assisted work.
Windows 10/11
Version: 1.7.46 (user setup)
VSCode Version: 1.99.3
Commit: b9e5948c1ad20443a5cecba6b84a3c9b99d62580
Date: 2025-10-14T01:21:46.830Z
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
auto
3ef56123-2a21-48a2-8d60-e751b6ae08fa
This is the second critical bug in less than a week.
The first one caused total loss of chat and Agent Mode history; now, this serialization error makes Cursor completely unusable.
It’s unacceptable for paying users to face repeated data loss and functionality failure at the core of the product.
Please escalate this ticket as a critical incident, not a feature bug, and provide:
A public acknowledgment that this issue is widespread;
A timeline for a hotfix or rollback;
A clear explanation of root cause and prevention measures.
Yes - Cursor is unusable
Hi everyone,
It’s concerning to see that this issue has been open for several months with no clear resolution or public update.
Multiple paying users are affected, and this error completely breaks the core Chat and Agent functionality of Cursor.
At this point, it would be fair to expect an official statement or progress update from the engineering team — even if it’s just an ETA, a root cause summary, or confirmation that a hotfix is in progress.
It’s hard to justify continuing to rely on Cursor professionally when critical bugs stay unresolved for months.
We all understand that beta features can have issues, but this one affects the main product experience, not just experimental tools.
Please provide a concrete status update, or escalate this internally as a priority production issue.
Request ID: ac50617f-11e1-411d-8572-dc6bb1b893cc
Cursor IDE
provide simple prompt
open cursor, enter prompt, recieve error.
no error
Windows 10/11
version: 1.7.46
vscode version: 1.99.3
Request ID: 66ccf2f8-6417-4a5d-a68a-e7a2ab4b4640
ConnectError: [internal] Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools
at vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:7349:369901
Yes - Cursor is unusable
Cursor IDE
provide simple prompt
open cursor, enter prompt, recieve error.
no error
Windows 11
Version: 1.7.46 (system setup)
VSCode Version: 1.99.3
Commit: b9e5948c1ad20443a5cecba6b84a3c9b99d62580
Date: 2025-10-14T01:21:46.830Z
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
Request ID: ef965a73-35ae-471e-8f82-108a3b6d77fc
ConnectError: [internal] Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools
at vscode-file://vscode-app/c:/Program%20Files/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:7349:369901
Yes - Cursor is unusable
Cursor IDE
I ask cursor to debug my code and it runs the file and loses connection. I am unable to resume the chat or respond in the chat. I can open a new chat and talk there.
Request ID: 226637c5-01b6-4964-a2ed-7a78aaf2b266
ConnectError: [internal] Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools
at vscode-file://vscode-app/c:/Users/redacted/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:7349:369901
I asked it to debug ffvship issues. the output for running a comparison is apparently very long for cursor as opposed to powershell. due to how it processes it.
[||||||||||||||||||||||||||||||||||] 4/4 IPS: 200[|||||||||||||||||||||||||||||||] 4/4 IPS: 1333.3[|||||||||||||||||||||||||||||||] 4/4 IPS: 1333.3[|||||||||||||||||||||||||||||||] 4/4 IPS: 1333.3[|||||||||||||||||||||||||||||||] 4/4 IPS: 1333.33
Windows 10/11
Version: 1.7.46 (user setup)
VSCode Version: 1.99.3
Commit: b9e5948c1ad20443a5cecba6b84a3c9b99d62580
Date: 2025-10-14T01:21:46.830Z
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
Auto
Request ID: 4bb7d67f-6310-45fc-9e8c-2e504df3789a
Yes - Cursor is unusable
Error still active. Very, very annoying.
”The crash originates in Cursor when it serializes a “request with tools.” This is a known issue reported by multiple users, often tied to tool-enabled chats and sometimes to payload size overflows (e.g., invalid int 32: 2147483648).”
A known, lasting, unresolved issue that now as a project impact? Not good.
Request ID: bfdf62a6-5315-4cf3-b362-47c654b57c6b
ConnectError: [internal] Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools
at vscode-file://vscode-app/c:/Users/bcorb/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:7349:369901
This bug still being unresolved is unacceptable. It pretty much renders Cursor useless.
When do you plan on fixing this error, doesn’t matter what version of the software you use, the error appears. 133 replies and still the error.
Telling people to check there internet connection or vpn is also not acceptable to the 95% of people who this doesn’t apply too. Did you just add that line because you truly dont know what is causing the issue?
Getting the same error since this morning. Might have worked for some time then getting the error again and again.
Short version: Cursor is asleep at the switch.
Users have reported the exact error below since July 31, 2025. Reports are still active today, October 17, 2025.
In many cases the IDE becomes unusable and work stops entirely.
There is no public fix, patch, or official post acknowledging the defect.
ConnectError: [internal] Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools
Cursor is going to hate me after this, but I don’t GAF. Let’s get into it shall we?
Kicking the hornets nest … 
First forum report with this exact string: July 31, 2025. The main thread and related posts remain active through early–mid October. Several GitHub issues opened last month and last week show the same signature. That is 78 days and counting.
A streaming failure on the aiserver.v1.StreamUnifiedChatRequestWithTools path. In practice, a chat turn never streams. The tab often locks and requires a full reset. Users describe the IDE as “unusable.” Some reports note charges on failed requests.
This is not intermittent fluff. It blocks basic prompts like “hello” and ends agent sessions mid-task. For teams using Cursor for interactive coding, lint-driven edits, or build orchestration, this is a mission-critical outage. Our own environment exhibits complete work stoppage with every prompt. Detailed reproduction and environment are documented in our notes.
The failure behaves like a serialization boundary issue on the streaming RPC. The most consistent triggers are large frames from tool output or long generations that are not chunked or backpressured.
Less likely, but still possible, is a schema mismatch that surfaces as a generic “serialization error.” These inferences match forum logs and stack traces referencing encode paths and int32 write boundaries.
These typically occur when strict .mdc rules and strict and highly precise prompts are used to prevent Cursor’s notorious and rampant issues with “memory drift”. Yes, Cursor likes to chase white rabbits 
worse than my Jack Russel on crack after a weekend ‘coke’, tequila and Red Bull. Seriously, memory drift with the Cursor platform is out of control. Anyway, back on the ranch …
Immediate mitigations
Server and platform changes
What Cursor should publish now
Independent users have already isolated high-signal repros, captured stack frames, and linked conditions that trigger failure.
The recommended fixes are standard for streaming systems that carry large, bursty payloads. This is 100% solvable. Leaving it open for 78 days has turned a defect into a sustained outage for many.
Please share exactly how you did this. I think this is the main problem.
I had the same issue. Check to make sure you do not have any spaces in your folder names. Replace any spaces with - and restart cursor.
I have found a way to consistently reproduce this bug. It seems to affect only Windows. I can only reproduce this consistently on one machine, but not my other. There might be another factor missing like default shell chosen, etc.
It does not seem to be based on what model you use, what version of Cursor (as all versions are currently affected)
Can you try running this to see if it breaks the chat?
1. Create a reprod.md file, with `---` repeated 50,000 lines. (please use terminal commands to create the file.)
`1..50000 | ForEach-Object { "---" } | Out-File -FilePath reprod.md -Encoding UTF8`
2. Run this command (this should break the chat, run it in terminal.)
`rg -n "^---" reprod.md | Select-Object -First 1`
Result: Connection failed. If the problem persists, please check your internet connection or VPN. Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools [internal]
To those affected and watching this, please try running this prompt to see if you can reproduce it as well. I can consistently reproduce it with these instructions. If you are able to reproduce it consistently with these commands, please do share what your setup is like.
I had some very explicit cursor rules that always changed directory to the workspace directory before running any powershell commands, however surprisingly this suddenly stopped working in some cases
Because this is all related to having a space in a folder name, I just decided to remove the space from my folder name and all is well again.
Honestly I think that’s just the best solution for now: Use other characters like dashes instead of spaces in your folder names.