“Customization could not be loaded” error with VSTO

ERROR: “Customization could not be loaded because the application domain could not be created.”

If you are working on an Excel (or other Office, I guess) VSTO AddIn / PlugIn project using C# and encountered this error, you may want to check that you are using the right platform (x86 vs x64) in your Configuration Manager.

I have x64 Office 2010 installed and saw this error when I am trying to run the x86 plugin today.

3-28-2014 4-17-19 PM