Many thanks for this step by step insight. The level of incompetence displayed by the developer program enrollment process has been mind boggling. Even the poor people in tech support apparently only see the original useless error message when inspecting enrollment logs. They don't give you a way to retry. And it might have roots in the fact that I originally gave them a made up birth date to iTunes some 15 years ago. (Who gives their real birth date to random web sites?). They also reached deep into iTunes to retrieve an ancient land line phone number used to associate with the original credit card. Probably used that mismatch as evidence of fraud.

I've seen the same thing. Been trying all combinations of credit cards, phone number, app/web, contact support and they just say "it failed". Process never gets to the payment stage, always "an unknown error occurred".

@eskimo, No one here on DevForums can help you with enrolment and account issues. You need to escalate this with Developer Programs Support I've tried this, even asked the last contact to escalate the problem, but the result was just a manager with no more help than previous contacts, and she was just anxious to dump the call since she had no solution. (I was very polite to everyone). (US-Based, multiple apple IDs, multiple IOS devices, multiple credit cards, new accounts, old iTunes accounts, developer app, web browser, - nothing! signup never completes: "Your enrollment in the Apple Developer Program could not be completed at this time. " or "An unknown error occurred".)