Hey, thanks for the report.
This is a known issue with Windows terminals. The error happens when the Agent runs commands and gets an incorrect exit code (-1), which gets converted to the unsigned int (4294967295) and breaks protobuf serialization on the client side.
Try this workaround:
- Close Cursor completely
- Open Settings with
Ctrl + , - Find
terminal.integrated.defaultProfile.windows - Set it to “Command Prompt” instead of PowerShell
- Restart Cursor
Sadly, based on other reports, this doesn’t always help, especially for long commands. The team is aware of the issue. Related threads:
- Cursor Agent gets stuck in “Connection failed” loop after PowerShell output-truncation pipeline; local protobuf serialization fails (invalid int 32: 4294967295)
- Connection Error - Serialize Binary (more users confirmed the bug)
You can subscribe to Connection Error - Serialize Binary for updates on the fix.