If error message "Unable to transfer this registration as the event payment account has changed. Please contact your organizer to cancel this registration and create a new registration" pops up during a transfer process, the reason is that the event payment account has been changed after participants registered.
Once the event payment account is changed, participants who registered before the change can not make changes which involve price, including transfer categories, transfer registration to someone else, refund and etc. The participants who registered after the change won't be affected.
If the registration has to be transferred, the event director needs to cancel the registration without refund (see Cancel Registration Without Refund), and then create a new registration without payment by applying a 100% discount code (see Create Discount Code).
