Compil error CS8179 using a "tuple" after updating Visual Studio and SDK 5.0.202

Question

I updatet my Visual Studio 2019 and the SDK 5.0.202.

But now I get compile errors using tuples:
The error shown: "Error CS8179 Predefined type 'System.ValueTuple`3' is not defined or imported"
I program in C#.

The statement I typed is:
public (string, int, double?) getMyFact(int? fact, string documentType)
note: "double?" is a nullable double.

Before the Visual Studio and SDK update this was no problem and was compiled correctly.
What goes wrong? What should I do to get this statement compiled properly?

Thnx!

Answer 1

Thanks for both reply's.

I think I do not quite understand the difference between the Visual Studio version and the SDK-version. Even don't know what the relation between those two is.

However, I got the problem solved by searching the folders for the references to the version and:

• downloading the 4.8 version explicitely, rather than the 5.0.202;
• in the files "App.config" and "MyProject.csproj":
  change the references "4.6.1" (or others) into "4.8";
• delete the hidden folder ".vs"

Now starting Visual Studio and compiling succeeded!

Thanks for all assistance!
Hans