There haven't been any reports with such an error message in the past.
It appears Apple have introduced some changes to their backend the last week as there are multiple reports of this error at the Apple Support Community
site. This affects all iOS developers, not only AppBuilder users and we are not sure what is causing it or if this is a bug at Apple's side. Please, write to the Apple app review team, provide them your app id and describe your error. If they can share what is causing the problem and it is app related, we will be glad to help.
Let me know the results.