Not sure what exactly you're doing here but it looks like custom Excel reports.
Your connection string looks similar to what I have on the Excel reports deployed from GP, just a bit different:
Provider=SQLNCLI11.1;Integrated Security=SSPI;Persist Security Info=True;Initial Catalog=T185C;Data Source=DESKTOP-03KE9TQ;Use Procedure for Prepare=1;Auto Translate=True;Packet Size=4096;Workstation ID=DESKTOP-03KE9TQ;Use Encryption for Data=False;Tag with column collation when possible=False;MARS Connection=False;DataTypeCompatibility=0;Trust Server Certificate=False;Application Intent=READWRITE
This is from one of my Excel reports deployed to a C:\ path on my desktop, so a connection string to a UNC path would be slightly different. You could look at our default Excel Reports' data source/connection string for an example.
We don't usually see this message with Excel reports, so I don't have much more.
Looking online, I see this message can be caused by everything from network to Excel version to the Power Pivot add in being enabled and more.
Hopefully this gets you going in the right direction.......maybe others in the Community have more.......
Thanks
André Arnaud de Cal... 291,280 Super User 2024 Season 2
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