Visual Studio 2010: Could not resolve mscorlib for target framework '.NETFramework,Version=v4.0'

Question

We are currently migrating all our solutions from 2005 to 2010 (that\'s right, we\'re skipping 2008!). We are also changing our file structure to make some more sense (some

Answer 1

I ran in to this problem today, and it proved to be caused of too long filenames in the project.

This, in turn, was caused by some service references. When a service reference is imported or updated, visual studio generates .datasource files, where the filename is the fully qualified name. This means really long names in some instances.

By googling around, I found hints that it was safe to delete these files. Check this or this out.

Deleting these .datasource files removed the problem.