Serialization error

Bug Reports
1

Describe the Bug

Request ID: 014db01a-134a-4461-9470-89a01b79fe77
ConnectError: [internal] Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools
at vscode-file://vscode-app/tmp/.mount_CursorTy1eVs/usr/share/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:4846:222865

Steps to Reproduce

any agent request to opus or sonnet from russian ip or vpn

Expected Behavior

agent working

Operating System

Linux (Ubuntu 24.04)

Current Cursor Version (Menu → About Cursor → Copy)

Version: 1.3.5
VSCode Version: 1.99.3
Commit: 9f33c2e793460d00cf95c06d957e1d1b8135fad0
Date: 2025-07-30T00:32:27.448Z
Electron: 34.5.1
Chromium: 132.0.6834.210
Node.js: 20.19.0
V8: 13.2.152.41-electron.0
OS: Linux x64 6.11.0-29-generic

Does this stop you from using Cursor

Yes - Cursor is unusable

4 Likes
2

try 1.3.5 or 1.3.6 same issue

3

plz fix it, i can’t work

1 Like
4

Can’t work with any models, with auto too

5

Describe the Bug

After last update I’m constantly receiving the following error amid the agent’s thinking

Request ID: b42c7f0c-1a92-4abf-a09e-18888b21c7b4
ConnectError: [internal] Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools
    at vscode-file://vscode-app/c:/%USERPROFILE%/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:4846:222865

On every prompt. Cannot use the agent.

Steps to Reproduce

I have a service repository with several Typescript files. Was doing a prompt with 4 files in context

Expected Behavior

To not explode while the agent thinks

Screenshots / Screen Recordings

Operating System

Windows 10/11

Current Cursor Version (Menu → About Cursor → Copy)

Version: 1.3.7 (user setup)
VSCode Version: 1.99.3
Commit: 5d56108ff2401c28f239aa2a527ef424ce7719a0
Date: 2025-07-31T04:16:31.276Z
Electron: 34.5.1
Chromium: 132.0.6834.210
Node.js: 20.19.0
V8: 13.2.152.41-electron.0
OS: Windows_NT x64 10.0.26100

Does this stop you from using Cursor

Yes - Cursor is unusable

2 Likes
6

workbench.desktop.main.js:2648 [composer] Error in AI response: undefined ConnectError: [internal] Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools at workbench.desktop.main.js:4846:222865

Caused by: Error: invalid int 32: 2147483648 at aUi (workbench.desktop.main.js:441:73111) at G0o.int32 (workbench.desktop.main.js:442:12768) at ukt (workbench.desktop.main.js:442:19802) at X0o (workbench.desktop.main.js:442:18905) at Object.writeMessage (workbench.desktop.main.js:442:16669) at E6t.toBinary (workbench.desktop.main.js:441:75159) at Q0o (workbench.desktop.main.js:442:19723) at X0o (workbench.desktop.main.js:442:19003) at Object.writeMessage (workbench.desktop.main.js:442:16669) at J6t.toBinary (workbench.desktop.main.js:441:75159) at Q0o (workbench.desktop.main.js:442:19723) at X0o (workbench.desktop.main.js:442:19003) at Object.writeMessage (workbench.desktop.main.js:442:16669) at h8t.toBinary (workbench.desktop.main.js:441:75159) at Q0o (workbench.desktop.main.js:442:19723) at X0o (workbench.desktop.main.js:442:18985) at Object.writeMessage (workbench.desktop.main.js:442:16669) at d8t.toBinary (workbench.desktop.main.js:441:75159) at Q0o (workbench.desktop.main.js:442:19723) at X0o (workbench.desktop.main.js:442:18985) at Object.writeMessage (workbench.desktop.main.js:442:16669) at Tjt.toBinary (workbench.desktop.main.js:441:75159) at Q0o (workbench.desktop.main.js:442:19723) at X0o (workbench.desktop.main.js:442:19003) at Object.writeMessage (workbench.desktop.main.js:442:16669) at fUt.toBinary (workbench.desktop.main.js:441:75159) at Q0o (workbench.desktop.main.js:442:19723) at X0o (workbench.desktop.main.js:442:19003) at Object.writeMessage (workbench.desktop.main.js:442:16669) at Qzt.toBinary (workbench.desktop.main.js:441:75159) at Q0o (workbench.desktop.main.js:442:19723) at X0o (workbench.desktop.main.js:442:18985) at Object.writeMessage (workbench.desktop.main.js:442:16669) at Gzt.toBinary (workbench.desktop.main.js:441:75159) at Q0o (workbench.desktop.main.js:442:19723) at X0o (workbench.desktop.main.js:442:18985) at Object.writeMessage (workbench.desktop.main.js:442:16669) at Szt.toBinary (workbench.desktop.main.js:441:75159) at Q0o (workbench.desktop.main.js:442:19723) at X0o (workbench.desktop.main.js:442:19003) at Object.writeMessage (workbench.desktop.main.js:442:16669) at izt.toBinary (workbench.desktop.main.js:441:75159) at workbench.desktop.main.js:4846:222836

submitChatMaybeAbortCurrent @ workbench.desktop.main.js:2648
8

Hi @Sephira and welcome to Cursor Forum.

Thank you for your bug report. We have released several further improvements and bug fixes, Could you please update to latest version? it should be 1.3.8.

Please make sure to try a new chat and let me know if the issue still remains.

1 Like
9

hi @Artem_Hudolej and welcome to Cursor Forum.

Thank you for your bug report, I have moved it here as its more relevant.

More details about your issue are required so we can investigate and fix it:

  • Which Cursor version and OS version do you use?
  • Which model did you use when the error occurred?

Please update to latest 1.3.8 as it contains several bug fixes and let me know if the issue still happens.

10

Same issue here
I updated to 1.3.8 already

Request ID: a3c9e0c4-27bf-4d5d-ac5d-88c32f5dd8e3
ConnectError: [internal] Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools
at vscode-file://vscode-app/c:/Users/user/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:4846:222865

1 Like
11

Thank you @Macypher & @David_Hernandez, added your Request ID to the report.

12

I frequently encounter this error mid-response in Cursor AI, regardless of the model I employ, be it GPT-4o or Claude 3 Opus. My internet connection is stable, and no VPN is active.

Error Message:

Connection failed. If the problem persists, please check your internet connection or VPN.
Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools [internal]
Request IDs:

ae322041-0112-459d-9f54-8e17520903f6
e7dc9bc1-89c5-4006-867f-9a8568382d16
b6f327ea-c865-477a-a4a8-8a9cc16b946b
b4fc2c7e-4dbd-4fca-b381-448bc0ab77d8

Steps to Reproduce

  1. Submit a request to Cursor AI for the generation of a lengthy response or code.
  2. Approximately halfway through the generation, the stream abruptly terminates with the aforementioned error.
  3. This error manifests across all models, even after clearing the local cache.

Expected Behavior

The response should complete seamlessly without interruption.

Operating System

Windows 10/11

Current Cursor Version (Menu → About Cursor → Copy)

Version: 1.3.8 (user setup)
VSCode Version: 1.99.3
Commit: a1fa6fc7d2c2f520293aad84aaa38d091dee6fe0
Date: 2025-07-31T21:46:17.109Z

14

@KARASSCO_200 thank you, added your report as well.

15

I updated to 1.3.8 and model claude-4-sonnet

1 Like
16

Already I updated to 1.3.9 and model claude-4-sonnet!

But error again.

Request ID: a4bdf0c9-7fe3-4acd-be30-70685cd39dec
ConnectError: [internal] Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools
at vscode-file://vscode-app/tmp/.mount_cursor2dWzj2/usr/share/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:4846:222865

Network diagnostics - all OK.

If create new chat - all worked.

And after restart Cursor - error was hide.

17

Thank you for the update. I have added the info to our internal ticket.

18

Same serialization issue. 1.3.9 on Windows 11. Appears (for now) to be isolated to Anthropic models. Network diagnostics - all OK.

19

Describe the Bug

I am getting this in Agent mode. Lost a lot of tokens

Connection failed. If the problem persists, please check your internet connection or VPN
Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools [internal]
(Request ID: 8f298ee6-4b2a-4f99-9123-97849f64b08e)

Haiku works ok

Steps to Reproduce

Just ask to do something

Operating System

Windows 10/11

Current Cursor Version (Menu → About Cursor → Copy)

Version: 1.3.4 (user setup)
VSCode Version: 1.99.3
Commit: bfb7c44bcb74430be0a6dd5edf885489879f2a20
Date: 2025-07-29T03:59:10.762Z
Electron: 34.5.1
Chromium: 132.0.6834.210
Node.js: 20.19.0
V8: 13.2.152.41-electron.0
OS: Windows_NT x64 10.0.19045

1 Like
20

Same here. Cursor 1.4.1 on Windows 11 using claude4-sonet. Worked fine until this morning. Now every query gets interrupted after the first few response sentences:
Request ID: xxxxx
ConnectError: [internal] Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools
at vscode-file://vscode-app/c:/Users/…/workbench.desktop.main.js:xxxxx

21

Describe the Bug

After requesting Cursor to complete a task, when Cursor finishes the TODO items and I discover an error that needs to be fixed, a “connection failed” error occurs when attempting to make corrections. everytime

Connection failed. If the problem persists, please check your internet connection or VPN

ConnectError: [internal] Serialization error in aiserver.v1.StreamUnifiedChatRequestWithToolsat vscode-file://vscode-app/Applications/Cursor.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:4918:250162

Request ID: ef51fae5-8581-4020-84ab-1c3c5da84473

I already reinstalled cursor, reset the macOS network setup (i don’t use VPN).

EDITED

on console log

[AiService] streamResponse ConnectError: [internal] Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools
at workbench.desktop.main.js:4918:250162Caused by: Error: invalid int 32: 2147483648

when this overflow bug triggered, i can not use cursor agent until restart cursor. with full of Error: invalid int 32: 2147483648 messages

I think this bug came with showing token limit circle bar under the agent message box.

if you need more test plz tell me.

Steps to Reproduce

Submit a task/request to Cursor
Wait for Cursor to complete the TODO items
Identify an error in the completed work
“Found 2 errors in ****/” message appears
“Connection failed” error appears

Expected Behavior

Just keep work & fix errors

Operating System

MacOS

Current Cursor Version (Menu → About Cursor → Copy)

버전: 1.4.2 (Universal)
커밋: 1.99.3
날짜: 07aa3b4519da4feab4761c58da3eeedd253a1670
Electron: 2025-08-06T19:23:39.081Z (12시간 전)
ElectronBuildId: 34.5.1
Chromium: undefined
Node.js: 132.0.6834.210
V8: 20.19.0
OS: 13.2.152.41-electron.0

Additional Information

console log
[composer] ToolFormer: error in toolWrappedStream undefined
[AiService] streamResponse ConnectError: [internal] Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools
[composer] Error in AI response: undefined ConnectError: [internal] Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools
[composer] Failed to get complete AI response

Does this stop you from using Cursor

Yes - Cursor is unusable

22

[AiService] streamResponse ConnectError: [internal] Serialization error in aiserver.v1.StreamUnifiedChatRequestWithTools
at workbench.desktop.main.js:4918:250162Caused by: Error: invalid int 32: 2147483648

According to the console logs, it appears that some value used in communication is overflowing int32(maybe 20k limit token number something?), which causes the underlying issue. However, this gets caught at the network layer and continuously displays as a “network error.” I had no idea about the real cause and kept resetting/reinitializing the network connection thinking it was a connectivity problem.

1 Like