This version of Visual Studio is unable to open the following projects

Unity Engine
1

4620259--432607--upload_2019-6-6_17-55-1.png

Unity 2019.1.5f1
VS 16.1.2

The issue appears with unity C# projects only =(

2

VS reinstallation has helped.

3

I did this 3 weeks ago, and now I have to do it again? I would like to know what causes this problem. Everything worked fine for a while but now I am back with the same problem.