PBIRS Report subscription fails inconsistently

[BrentMitchell]

We have a newly set up PBIRS with May 2020 installed over SSRS 2016 and report subscriptions aren't working consistently.

We've only published one report while we test the server. The report on a shared schedule only works about 40% of the time. About 60% of the time it generates the error:

Failed to load expression host assembly. Details: Could not load file or assembly 'Microsoft.ReportingServices.ProcessingObjectModel, Version=2020.5.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91' or one of its dependencies. The located assembly's manif

When it works everything is logged normally but when this error comes up, I can't find any logging anywhere. I can only see the error on the "ReportName">Manage>Subscriptions page of the reports portal which is why the end of the message is cut off.

I don't understand why it only works sometimes or what to do about it.

Thanks

[Jon-Heide]

Hi Brent - suggest you try installing PBIRS on a separate machine, and migrate the catalog DB from 2016 and attach to PBIRS. Ensure you don't try to add to a split RS scale-out farm, or dual purpose the same catalog DB. The error seems to be related to a mismatched version of a product DLL, potentially due to an upgrade issue. If the issue with this report persists after clean install, suggest contacting MSFT support. 

[BrentMitchell]

Thank you. I will update this post once I've had a chance to implement the suggestion.