Project not building after creating unit tests in visual studio?

Question

A product with lot of interdependence among projects. Initially creating unit test for one project. Successfully able to create tests and using InternalsVisibleTo() for accessing non-public class members of that project. But when I build the project, because it has dependencies its throwing errors. Before creating tests there were no errors.

List of errors:

Failed to load '..\\xxx1.dll' because it is not a valid .NET assembly : RegAsm

The command "%SystemRoot%\\Microsoft.NET\\Framework64\\v4.0.30319\\regasm" xxx1.dll /tlb:"..\\xxx1.tlb" /verbose" exited with code 100.

The output property is not set for the project. Please check to make sure you have specified valid combination.

Answer 1

Solved after changing "Solution platforms" to "x64". Since one project among dependencies was indirectly depending upon a project that needs to be build for x64 machine.