Warning on dependencies when create a new standard .NET project

Question

I have installed VS 2017 and I am sure all features related to.Net Framework, Core, C#, and ASP.NET are installed with others.

All I do is create a new project (.net standard class library) then the dependencies section is showing the warning (yellow triangle) sign. When I click on the dependencies visual studio freezes and close. If I try to work with any library I get the same error

cannot resolve symbol

Any ideas please?

When I try to build the solution, I get the following error

EDIT

I have also checked NuGet Package manager and found that the available source looks like below

Answer 1

Well, What I am going to say will sound CRAZY, but it is a fact and known issue and really hard to be found.

The problem is in the project path, the path for the project I have created contained a special character c:/users/Hussein Khalil(XXX)/PROJECT_NAME

when I created the project on a simple path c:/test/... everything is worked fine.

Hope this could help.