One interesting issue that showed its ugly head in my recent project was an unexpected exception that popped up on all visuals on a Power BI report. How it happened was quite strange; one moment all the reports were working fine. The next moment when a report visual was modified and deployed to Power BI, all the visuals start turning into a grey box with a cross, with a “See details” link. The details weren’t at all helpful. Just, “An unexpected exception occurred.”:
Clicking on the “Copy Details” link and pasting on a text editor, and quickly scanning through showed this:
And to make matters worse, all subsequent report loads, including that of other reports, puts the reports into hang, until Analysis Services is restarted. The cycle starts again when the offending report is opened again.
A little digging around pointed at a bug on SQL Server 2016 SP1 Analysis Services. I’m not sure if the problem occurs on a version prior to SP1, however there is a fix: SP1 CU5 (KB Article: KB4037354). Once installed the problem disappears. I tested the issue out on SQL Server 2017 Analysis Services, and this problem does not occur on SQL Server 2017.