Visual Studio 2017 - Could not load file or assembly 'System.Runtime, Version=4.1.0.0' or one of its dependencies

Question

I am using Visual Studio 2017 and am trying to create a .Net Standard 1.5 library and use it in a .Net 4.6.2 nUnit test project.

I am getting the following error...

Answer 1

This issue has many causes... in my case the problem was that in my web.config a tag adding the System.Runtime assembly:

but one package also added the same assembly as dependency with other version:

removing the tag from my web.config resolved the issue.