Dependency 'dependency1' of dependency ' dependency2' is not an assembly
The project system has determined that a particular dependency (dependency1) of an assembly (dependency2) is not a .NET assembly.
To correct this error
Reinstall Visual Studio (if the assembly came with Visual Studio or the .NET Framework).
- or -
Reinstall the appropriate third-party control.
This error will not prevent the project from building. However, a run-time error is possible.