Agent loses connection when building nextjs app

[joshhh (Josh)]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Auto agent throws a connection error whenever it’s told to build a nextjs app and push the changes to the repo.

Steps to Reproduce

ask the auto agent to “build the nextjs app to success then push all changes to the repo”

Expected Behavior

It should build, fix errors, then git add, commit, and push.

Operating System

Windows 10/11

Current Cursor Version (Menu → About Cursor → Copy)

Version: 2.3.8 (system setup)
VSCode Version: 1.105.1
Commit: 28e7b8993fa2568fb3cb377e67615eb068b893e0
Date: 2025-12-27T18:19:45.425Z
Electron: 37.7.0
Chromium: 138.0.7204.251
Node.js: 22.20.0
V8: 13.8.258.32-electron.0
OS: Windows_NT x64 10.0.26200

For AI issues: which model did you use?

Auto

For AI issues: add Request ID with privacy disabled

Request ID: a504c39f-e94e-4423-ae9f-09b94dc61251
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:12707:471142

Does this stop you from using Cursor

No - Cursor works, but with this issue

[deanrie]

Hey, thanks for the report.

This is a known issue. Other users have hit the same serialization error, and the team is working on a fix.

Workarounds:

1. Start a new chat, don’t continue in the same one
2. Or restart Cursor
3. Try splitting the task into smaller steps. Instead of “build and push”, ask it to build first, then do the git steps separately

Also, please check: Cursor Settings > Network > Run Diagnostics.

Let me know if this helps.

[joshhh (Josh)]

@deanrie This bug is persisting in 2.3.15. I’m only asking it to “npm build the dash” and it loses connection. The only fix is to restart Cursor and then ask the agent to continue. It seems the probability of it happening increases as the chat gets longer.

[deanrie]

Thanks for the update. Yeah, I can see the issue still happens in 2.3.15, even with short commands.

The team is already working on a fix. Like you pointed out, the longer the chat, the more likely it is to happen, and that helps with diagnosing it.

For now, the workaround is the same: restart Cursor and continue in a new or shorter chat. I know it’s inconvenient, but it helps reduce the chance of the error.