After upgrading our TeamCity server out test coverage builds are failing with an exception:
System.InvalidProgramException: Common Language Runtime detected an invalid program.
All other unit test configurations run fine on the same code. Looking at the logs the only difference we see is the dotCover version. Old and new both using Nunit 2.6.2 under .NET 4.0 x86. Coverage builds still work fine on old server using the same code. The agents were just pointed to the new server, no OS or tools changed.