Your Compute session is disconnected

Hi Ojicletus ,

This error means your Fabric capacity has reached the concurrent Spark jobs limit. This is a SKU/capacity-level throttling issue, not necessarily a problem with your code.

Learn more here: https://learn.microsoft.com/fabric/data-engineering/spark-job-concurrency-and-queueing

I would recommend reviewing the following:

1. Review and cancel active jobs

Go to Workspace Settings → Data Engineering/Science → Spark settings → Jobs and cancel any non-critical Spark jobs.

There are often "zombie" notebook sessions consuming Spark slots without doing anything useful.

https://learn.microsoft.com/fabric/data-engineering/job-concurrency-queue-monitoring

2. Activate High Concurrency (if applicable)

This can help improve Spark session utilization and reduce concurrency-related issues.

https://learn.microsoft.com/en-us/fabric/data-engineering/configure-high-concurrency-session-notebook

3. Review Spark compute configuration

In fact, I ran into the same error today and immediately thought of you.

In my case, I adjusted the Spark configuration. I had a Medium node running on an F4 capacity, and I changed it to Small, also adjusting the number of nodes. That resolved the issue for me.

Give it a try and let us know if it works for you: https://learn.microsoft.com/en-us/fabric/data-engineering/environment-manage-compute

Additional references that may help:

https://learn.microsoft.com/fabric/data-engineering/job-queueing-for-fabric-spark

https://learn.microsoft.com/fabric/data-engineering/autoscale-billing-for-spark-overview

https://learn.microsoft.com/fabric/data-engineering/troubleshoot-permissions-capacity#capacity-and-r...

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Thank you!