Hi @KatBous ,
It appears when a Microsoft App has an Exception from HRESULT: 0x8000FFFF (E_UNEXPECTED)
Seriously though, we're going to need a bit more context in order to help.
Which app are we talking about - Excel or Power BI Desktop? When does the app throw this error? Is it when refreshing a PQ preview? When applying changes to the data model? When selecting a certain step in your query?
If you can can describe what you're doing at the time the error is thrown, this will help narrow down the cause.
Quite often these types of errors are transient and can be fixed with the old 'switch it off and back on again', but I assume you've already tried that?
Now accepting Kudos! If my post helped you, why not give it a thumbs-up?
Proud to be a Datanaut!