Error in Visual studio 2017: "The following project is out of date", what should I do?

Question

C++ / C#

Error in Visual studio 2017: "The following project is out of date", what should I do?
Explain in detail.

Answer 1

If it is the code that interests you, then open the project file in notepad and change the version to the one you need (you can create a new project and see it in the created file).