Notebook threw MwcTokenValidationException error when connecting lakehouse

[VVT]

I tried to connect my notebook with lakehouse source but it failed to connect with MwcTokenValidationException error. I have been working with Notebook for some time and never seen this error before. I did some research and it seems to be an error from Microsoft. Could you please help? Thanks

[VVT · Accepted solution]

Just want to give an update on this one. This issue just went away today. I didn't do anything on my end. 

[v-hashadapu]

Hi @VVT,

Thanks for the update. Happy to know your issue is solved. Can you please mark the helpful reply "Accept as solution" for other community members to find the helpful answer regarding the issue easily.

[v-hashadapu]

Hi @VVT , Thank you for reaching out to the Microsoft Community Forum.

This error often occurs when the authentication token used by your notebook has expired or become invalid. To fix this, sign out of the Microsoft Fabric portal completely, then sign back in to refresh your credentials. Next, open your notebook, go to the Lakehouse explorer in the left panel, remove the current Lakehouse connection by clicking the three dots and selecting “Remove,” then re-add it by clicking “Add Lakehouse” and selecting your Lakehouse. This triggers a new authentication flow. Run a simple test query like df = spark.read.format("delta").table("<lakehouse_name>.<schema>.<table_name>") to confirm the connection. This should resolve most token-related issues.

If the token refresh doesn’t work, the issue might be due to insufficient permissions. In the Fabric portal, navigate to your workspace, click Manage Access and confirm your account has Contributor or Member permissions. Then, go to the Lakehouse, click the three dots, select Manage permissions and ensure you have read/write access to tables or files. If the notebook and Lakehouse are in different workspaces, verify you have access to both. After updating permissions, restart your notebook kernel and retry the connection. This step ensures your account is authorized to access the Lakehouse.

A misconfigured connection can also trigger this error. In your notebook, ensure the Lakehouse is set as the default by pinning it in the Lakehouse explorer. If it’s not the default, use the absolute ABFS path for queries, like df = spark.read.format("delta").load("abfss://<WorkspaceGUID>@onelake.dfs.fabric.microsoft.com/<LakehouseGUID>/Tables/<table_name>"). You can copy the ABFS path from the Lakehouse’s folder menu. If using the SQL analytics endpoint, verify the connection string in the Lakehouse settings and test it with a simple query. Restart your notebook session and test again to confirm the setup is correct.

If this helped solve the issue, please consider marking it 'Accept as Solution' so others with similar queries may find it more easily. If not, please share the details, always happy to help.
Thank you.

[VVT]

Hi, thank you for providing all the options but unfortunately it doesn't work. I tried logging out and logging in but error is still there.

I am an admin of the workspace. I have Read, Write, Reshare, Execute, ReadAll, ViewOutput, ViewLogs, SubscribeOneLakeEvents to the lakehouse.

I also get this error when loading the lakehouse. If I switch it to SQL endpoint, there is no issue at all.

The interesting part is with this error, I am not able to view the tables/schema but there is no issue when querying the data (through notebook or sql endpoint).

I have another workspace with similar permission and dataset. I don't have any error when loading the lakehouse.

Is this an error from Microsoft or is the lakehouse corrupted?