I got the same message, with no detailed description after trying to enroll to the developer program.I got in phone with the support team and they've found the problem with my account. The problem was that my appleID first name was the string "iOS". After renaming it, the error message was gone.The problem is that this must be one of many verifications that doesn't have any description to the end user. So if that's not your case, I advice you to get in contact with developer support via email or phone call (the called me less than 30s after I requested).I hope Apple provides better error messages, but in the meanwhile, the support must solve your problem.Best.