Common solutions to this issue: The specified version of Microsoft.NetCore.App or Microsoft.AspNetCore.App was not found.
Looking on the server in the Event Viewer Application log I see a message “can’t start myappname.dll”
Solution: I attempting to add debug settings to the web.config, I cut/pasted from another web.config. Thus, the program name, myappname.dll, was NOT the correct name.
We got this coding against the Hyland OnBase api. So code like this:
Core.FileTypes.Find(x);
Will work if x is “MS Word Document”, but if it is not a known type then x will be null. Passing x later into CreateStoreNewDocumentProperties(..) and then calling StoreNewDocument(..) gives us this lovely error above.