Invalid package family name: Appname_q6srzhww6szzg (expected: Appname_e0kvyw5mrygy8)

Problem:

Trying to submit a Windows Phone Silverlight 8.1 app to the Windows Store and getting this error.
I was puzzled by the error so I started to play around with the Package.appxmanifest file.

Solution:

Listed with this error was also a related Invalid Publisher Name which was the underlying issue.  I had mistyped my publisher name.  This should be 36 character GUID and I had only 32 characters.
Once I had corrected the incorrect publisher name, the package family name was corrected.  This helped me understand that the package publisher GUID is being used to generate the unique id tacked onto the end of the package family name.

Needed to use the correct publisher name.  This is listed on your app identity page https://dev.windows.com/en-us/dashboard/apps/{App ID}/Identity

Source:

See my post coming later this week...