Describe the Bug
Installing the Jupyter extension (ms-toolsai.jupyter) fails on Cursor 2.5.20 with the error “[object Object]”. The root cause is a corrupt signature file (sigzip) served by marketplace.cursorapi.com.
The sigzip for ms-toolsai.jupyter v2025.4.1 is only 64 bytes of plaintext (kaggb5fd0hz9l7fjohvr…) instead of a valid zip archive. The installer tries to verify the signature, fails with “End of central directory record signature not found”, and rolls back the entire install including all successfully-extracted dependency extensions.
From remoteagent.log:
[warning] Failed downloading sigzip. End of central directory record signature not found. Either not a zip file, or file is truncated.. Retry again... ms-toolsai.jupyter[error] Error while installing the extension ms-toolsai.jupyter End of central directory record signature not found.
The VSIX itself (12MB) is a valid zip. The sub-extensions (jupyter-keymap, jupyter-renderers, etc.) install fine individually. Other extensions like ms-python.python and esbenp.prettier-vscode also install fine — their sigzips are not corrupt.
Steps to Reproduce
Connect to a remote SSH workspace via Cursor
Run cursor --install-extension ms-toolsai.jupyter
Observe [object Object] error
Operating System
MacOS
Version Information
2.5.20 / VSCode 1.105.1
Does this stop you from using Cursor
Yes - Cursor is unusable