C# – Could not resolve mscorlib for target framework ‘.NETFramework,Version=v4.6.1’

I just had the same problem. Visual Studio isn't building the project that's being referenced.

Written Instructions:

1. Right click on the solution and click Properties.
2. Click Configuration on the left.
3. Make sure the check box under "Build" for the project it can't find is checked. If it is already checked, uncheck, hit apply and check the boxes again.
4. (Optional) You had to do it for both Release and Debug modes on the solution properties.

Screen capture Instructions:

• They say a picture is worth a thousand words. Click on the GIF to zoom in, and hopefully it will be easy to follow:

It could be that the path to your solution is too long:

Meaning:

C:\MyProject\Folder\SubFolder...

should be Under "256 Character".

http://wcfvs.blogspot.com/2011/04/could-not-resolve-mscorlib-for-target.html

I found this thread when I had the same issue but had no reference issues. I found the link above and it solved my problem. Hopefully this will help someone else who comes here with the same problem.