I am trying to move a large Visual Basic .NET project from VS 2008 to VS 2019 Community Edition. In VS 2019, I am getting huge numbers of errors like
Requested operation is not available because the runtime library function 'System.Runtime.CompilerServices.AccessedThroughPropertyAttribute..ctor' is not defined.
Other functions are named on other occasions, such as "System.Runtime.CompilerServices.DateTimeConstantAttribute..ctor".
Even more strangely, I'm getting error BC30002, "Type 'System.String' is not defined", and the same error for other types (Void, Int32, DateTime, Decimal, etc.).
Clearly, some sort of reference linking the Windows forms app to runtime modules isn't getting loaded, but I can't figure out what's missing. I've looked at the VS 2019 version and the VS 2008 version, and the project references seem to match. Can you offer suggestions of how to get them properly loaded, and eliminate the current 75,000(!) errors?