There was an error uploading your .pbix file on new 1.18.8683.7488 Report Server version

[jrr6359]

Upgraded our Power BI Report Server to version 1.18.8683.7488 released October 10, 2023. I also downloaded the new Power BI Desktop for Report Server version 2.121.903.0 released September 27, 2023. 

I get the error "An error has occurred. There was an error uploading your .pbix file. Verify that the file has not been corrupted and that the file extension matches the format of the file" consistently now.

Things I've tried to fix the issue:

1. Looked at the msmdsrv log file; nothing out of the ordinary here.
2. Restarted the Power BI Report Server service.
3. Tried editing an existing working Power BI report and re-saving to our server, which throws the same error above.
4. Used the web portal Upload button, which throws the same error above.

Out of options as to what to do to fix this error. Please help!

[d_gosbell]

I have the same versions and cannot reproduce this issue. I think you should raise a ticket with Microsoft Support so that they can help dig into this. Or you could try checking some of the log files in C:\Program Files\Microsoft Power BI Report Server\PBIRS\LogFiles starting with the ReportingServicesServer* and RSPortal* files.