The 'ProviderPackage' package did not load correctly

Question

I installed Visual Studio 2012 and at a later date Update 2. After installing Update 2, when I load any project, I get the following error:

Answer 1

In my case the problem appeared after I installed Visual Studio 2015. From that point nor 2015, nor previous versions of Visual Studio would load. The problem was the PATH environment variable exceeding the MAX length.

I shortened it to less than 2048 and restarted the machine. Visual Studio started loading, but with some errors still. Lastly run the devenv /setup, and all is back to normal.