Windows Phone Registration Issue Fixed For Devices Registered With a Different AppHub ID

Microsoft fixed a bug that was preventing phones that were unlocked under a different AppHub account from being re-registered with a new ID, unless the original account holder would un-register it.

Ultimately, this applies to developers who might’ve had their devices unlocked by someone else other than themselves.

All you have to do now is simply use the Windows Phone registration tool to re-register the device with a different Microsoft ID that is associated with a valid AppHub account.