Forum Discussion
An unexpected error occurred (file '', line , function '')
Hi,
After installing on several devices and noticing that some returned errors while others didn’t, I compared the system information of each one and found that the issue, in this case, is related to AVX CPU extension support. One of the VMs didn’t inherit this extension from the host, and once it was enabled, the error disappeared.
We can conclude that the error is related to CPUs lacking the AVX extension.
Best Regards.
Hi Nuno_Santos
After updating to the May 2025 version of Power BI Report Server, you are encountering the error message 'An unexpected error occurred (file '', line , function '')' in long-standing reports, and the issue appears to be tied specifically to date slicer visuals. This kind of error typically indicates a rendering or compatibility issue introduced by changes in the underlying visual or report server engine. Microsoft periodically updates the slicer functionality—especially for date-based slicers—to enhance usability or performance, and these updates can inadvertently break backward compatibility with older visuals that were created or configured differently in previous versions of Power BI Desktop optimized for Report Server.
The fact that deleting and re-adding the date slicer resolves the error strongly suggests that the issue is with how the slicer metadata is stored in the report file, and that the updated server cannot correctly interpret or render the older slicer configuration. This is not uncommon when reports built with earlier Desktop versions are redeployed to a server with a newer rendering engine. To address this, the most reliable workaround is to open the affected report in the May 2025 version of Power BI Desktop (for Report Server), delete and re-add the date slicers, then re-publish the report. This ensures that slicers are regenerated using the latest structure compatible with the updated server version. Until Microsoft releases a patch or acknowledges this as a regression, this manual refresh of slicers is likely the safest way to ensure report stability.
