Windows Phone App Submission error: The [NeutralResourceLanguage] attribute is missing on the entry assembly. (2003)

The Windows Phone Marketplace has a big update yesterday. I tried submitting an update for one of my applications today and after selecting and uploading the assembly, I got a messaging saying that static validation completed with errors:

  • The [NeutralResourceLanguage] attribute is missing on the entry assembly.
    (2003)

To correct this error, you must go to your project properties in Visual Studio and the navigate to the Assembly Infomation. Once there, you must select a Neutral Language option from the drop down as seen below: