VS 2017 Metadata file '.dll could not be found

Question

I know there is another question with exact the same problem, but I went trough all those answers, and none helped me. :( (This was the question.)

I just created a new A

Answer 1

I had the same problem, even with no other errors showing on the "Error List" view after "Rebuild Solution". However, on the "Output" view, I saw the error that was behind the issue:

The primary reference "C:...\myproj.dll" could not be resolved because it was built against the ".NETFramework,Version=v4.6.1" framework. This is a higher version than the currently targeted framework ".NETFramework,Version=v4.5"

Once I corrected this, the issue was resolved.