Forum Discussion
UDF User Data Function - error when user has not access to function
I have created some UDF functions for writeback to Fabric warehouse from a Power BI report. This is working as expected.
Only thing that I'm not able to manage is an error message of some kind when someone presses the button that triggers the data function but isn't authorized for that function (new object in Fabric). Nothing happens but the user isn't made aware that nothing has happend and that he is not authorized to run use the function. It would be helpfull if that could be added somehow.
I initially tried to add the error message to the python of the UDF itself but that doesn't help as the UDF is never started in this case.
Has anyone a solution for this?
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
9 Replies
Hey SnoekLaurens ,
To handle the situation where a user is not authorized to run the UDF (User Data Function) in your Power BI report, and ensure they receive a proper error message. Solution you can try:
Check User Permissions Before Triggering the UDF: Before executing the UDF, you can check whether the user has the necessary permissions to access or trigger the function. This can be done in Power BI or within the Power Query/Power Automate flow.
Use Power Automate for Authorization Check:Create a flow to check user permissions before calling the UDF. If the user lacks access, the flow can send a notification or show an error message.
Example:
Create a Power Automate flow that gets triggered by the button click.
Before calling the UDF, add a step that checks the user's permissions.
If the permissions check fails, the flow can terminate and send an email, show a notification, or trigger a message in the Power BI report.
Error Handling in Power BI: Since you can't add error handling directly to the UDF if the function is never triggered, consider using DAX or Power Query to check if the user is authorized before showing any writeback options. You can show a custom message or disable the button depending on the user’s role or access level.
For instance, in DAX:
IF(HasUserPermission() = FALSE(), "You do not have permission to perform this action", "Writeback to Fabric Warehouse")
This approach provides visual feedback within the report before the user presses the button.
Feedback in the User Interface (UI): If the UDF is being triggered via Power BI's custom visuals or buttons, make sure that the UI is providing proper feedback to users about their access rights. You can design the button to display an error message (or disable the button) when the user doesn’t have access, using a combination of DAX and Power Automate.
For Detailed Information:
Using Power Automate to Check User Permissions
Power BI Button Action with Error Message
Azure Role-Based Access Control (RBAC) for Power BI
Power BI DAX Functions for Error Handling
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 AzamI'm using the new native writeback capability with the new UDF function in Microsoft Fabric so I'm not using Power Automate and also Power Query is not directly used for this purpose.
So option 3 seems suitable but I have no idea how to do that in Power BI. I have a button with the data function connected. How can I add this to that button?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
Thank you for reaching out to the Microsoft Fabric Forum Community.
Nasif_Azam thank you so much for your inputs.
SnoekLaurens - I hope the information shared was helpful to you. If your question has been answered, kindly mark the most relevant reply as the Accepted Solution. This small action can make a big difference for others who are looking for the same solution.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.
