Forum Discussion
Assistance Needed: Report Failing with Data Source Error (Microsoft.Data.Mashup.ErrorCode = 10335)
I’m reaching out because one of my reports has started failing with the following exception message:
Error: Data source error: Expression.Error: We cannot apply field access to the type Null.
Details: Microsoft.Data.Mashup.ErrorCode = 10335; Key = Tables.
The exception was raised by the IDbCommand interface.
I haven’t made any recent changes to the report or its data sources, so I’m unsure what might have caused this issue.
Could you please advise on possible causes or next steps to resolve it?
Thank you for your help,
Sunit
13 Replies
You lost access to the database schema, and as a result the list of tables comes back empty.
Thanks for your response. I have checked my access — it’s there. I also tried running the query on Questo, and it works fine. However, when I refresh the data in the Power BI report, it fails with the error mentioned above. Could you please help me with this issue?
What is Questo? What's the data source?
Hi v-sunitkumar ,
Thank you for reaching out to Microsoft Fabric Community.
Thank you lbendlin for the prompt response.
This happens when Power BI receives a null response from the Kusto connector - often due to a schema change, table rename, or credential mismatch. Please check that the table still exists, re-authenticate your Kusto connection, and confirm the same account has access in both Power BI and Kusto. If the dataset recently changed or grew in size, try reducing rows to rule out connector limits.
I ran this query in Kusto, and it’s working fine — I have access as well. The table definitely exists; otherwise, I wouldn’t be able to run the query in Kusto. Both accounts are the same in Kusto and Power BI. I’ve also updated my account, but the issue still persists. Yes size of power bi also near 700 MB.
Clear the cache in Power BI Desktop and do a schema refresh.
Hi v-sunitkumar ,
Thank you for reaching out to Microsoft Fabric Community.
Thank you lbendlin for the prompt response.
I wanted to check if you had the opportunity to review the information provided and resolve the issue..?Please let us know if you need any further assistance.We are happy to help.
Thank you.
Hi v-sunitkumar ,
May I ask if you have resolved this issue? Please let us know if you have any further issues, we are happy to help.
Thank you.
Issue still there we dont have any solustion yet.
Hi v-sunitkumar ,
As mentioned earlier, this error happens because Power BI is receiving null schema metadata from the Kusto connector, even though the query runs fine in Kusto. To fix it, clear the Power BI Desktop cache, clear Kusto permissions, reconnect, and refresh the schema. Also ensure your final Kusto query has a fixed projection (e.g., project Col1, Col2…) so the connector can infer a stable schema. If you are using msit.com, verify that you’re connecting through the correct internal Kusto endpoint.These steps resolve the Microsoft.Data.Mashup.ErrorCode = 10335 issue in most Kusto-Power BI scenarios.
If the issue still persists, I would suggest to raise a Support Ticket using below link:
Create a Fabric and Power BI Support Ticket - Power BI | Microsoft LearnThank you.
Hi v-sunitkumar ,
I wanted to check whether you were able to resolve the issue with the help of Troubleshooting steps..?If not did you had a chance to raise support ticket and resolve this issue? If so, please consider sharing the solution in the forum,this will help other members find the answer more easily.
Thank you.
Hi Team,
I haven’t found any solution for this issue yet. I’ve reviewed all the responses, but none of them have helped resolve the problem.This issue is not related to the database or access.
Could you please assist me with this?
Thank you,
Sunit
