What do Yellow Warning Triangles mean on Dependencies in Visual Studio 2017?

Question

I have just converted my PCL library to a new .Net Standard library and I have some Yellow Warning triangles on my Dependencies shown below:

During the conv

Answer 1

Restart Machine

I believe that my situation was that some process was not releasing certain dlls after a cache flush and then any acquisition of dlls failed due to that lock(?).

By restarting my machine and doing donet restore resolved the issue and I could build again without the missing package error.