Notebook new Standard or HC sessions won't start. This current seems to ocurre random

Hi ArjanFraaij ,

Thank you for reaching out to the Microsoft Community Forum.

Please check below things to fix the issue.

1. Restart the notebook kernel and re-run the cell. Try running the same notebook in a new session or workspace. Switch to High Concurrency sessions instead of Standard ones.

2. Increase timeout in Workspace Settings. Workspace Settings --> Data Engineering --> Spark Settings --> Jobs.

3. Clear browser cache and cookies. Use Microsoft Edge for best compatibility. Disable extensions that may block WebSocket connections.

4. Check with your admin to review the Spark job logs in the Fabric Admin portal and Capacity metrics at the time of failure.

Please refer below community threads.

Solved: Fabric Notebook disconnects when running a certain... - Microsoft Fabric Community

Solved: Session Startup Issue on Fabric for the Past 5 Day... - Microsoft Fabric Community

Solved: Re: Fabric Notebook Session Is Not Getting Created... - Microsoft Fabric Community

Solved: Re: Notebook Status - Stopped (Session Timed Out) - Microsoft Fabric Community

Solved: Notebook Session Issue - Microsoft Fabric Community

I hope this information helps. Please do let us know if you have any further queries.

Regards,

Dinesh