Forum Discussion
UDF User Data Function - error when user has not access to function
Hey SnoekLaurens ,
Since you're using the new native writeback functionality in Microsoft Fabric with UDF and not using Power Automate or Power Query, the solution should focus on enhancing the button’s behavior directly in Power BI. Steps to Add Error Handling to the Button:
Create a DAX Measure for User Permissions: First, create a DAX measure that checks whether the current user has the necessary permissions. This could be based on roles or a user table that tracks access levels.
UserHasPermission = IF( CONTAINS( UserPermissions[UserID], UserPermissions[UserID], USERNAME() ), TRUE, FALSE )Set the Button Action Based on the Permission Check:
You can use the UserHasPermission measure in the button’s Action property to control whether the UDF is triggered.
If the user does not have permission, you can set the button action to None or show a message indicating lack of access.
Use a Dynamic Tooltip/Message: You can also configure the button’s tooltip or dynamic text to inform the user about their permission status.
ButtonMessage = IF( [UserHasPermission] = TRUE(), "Click to writeback to Fabric Warehouse", "You do not have permission to perform this action" )Provide Feedback on the Button: Set the Visible property of the button based on the permission measure:
ButtonVisible = IF([UserHasPermission] = TRUE(), TRUE(), FALSE())
This way, the button can either be visible or hidden depending on the user's access level.
Implement these DAX measures in your Power BI report and link them to the button properties like Action, Visible, and Tooltip to manage user interactions based on their permissions.
If you found this solution helpful, please consider accepting it and giving it a kudos (Like) it’s greatly appreciated and helps others find the solution more easily.
Best Regards,
Nasif Azam
Hi SnoekLaurens
You're encountering a subtle but important usability issue in your Power BI writeback workflow to a Fabric warehouse using UDFs (user-defined functions): when an unauthorized user attempts to trigger a UDF via a Power BI button, nothing happens—no feedback, no error, and no indication of why the action failed. This silent failure occurs because Fabric’s execution engine doesn't even invoke the UDF if the user lacks the necessary permissions on the object (such as EXECUTE on the function or INSERT/UPDATE on the target table), meaning your attempt to handle the error inside the UDF has no effect—it never runs.
Unfortunately, Power BI doesn’t currently offer native error-handling or messaging feedback for button-triggered actions tied to external operations like SQL UDFs. Because the operation is not managed within the Power BI data model or DAX context, there’s no way to directly display an error or status message based on the failure of a background SQL action—especially one that's blocked at the permission level.
A possible workaround is to create a status-check mechanism in the database. For example, instead of calling the UDF directly, route the action through a logging or staging table where an initial write attempt is made with metadata (such as username, timestamp). If the user has permission, the write proceeds, and a success record is logged. If not, the write fails silently but the logging table remains unchanged. Then, in Power BI, you can create a separate query or visual that polls this log or status table and displays a status (e.g., “Write successful” or “No recent write attempt”), ideally personalized per user using USERNAME() or USERPRINCIPALNAME().
Alternatively, you can work with Power Automate instead of direct SQL-based UDFs. A Power BI button can trigger a Power Automate flow, which includes built-in error handling, permission checks, and the ability to return error messages or even post alerts via Teams or email. This introduces more transparency in the user experience but adds complexity.
In summary, due to security and architecture boundaries, you can’t handle permission-denied errors inside UDFs because they don’t run when blocked. Instead, build external mechanisms—either via status tables or automation workflows—to detect and communicate access issues back to the user in Power BI.