When the logic board is replaced in a Mac computer the technician is supposed to enter the serial number electronically into the system. The serial number should be scribed onto the case of the Mac, or located on a legitimate sales receipt.
If for some reason the serial number can't be entered electronically into the Mac, you will never be able to use Facetime.
If you have not had the logic board replaced, I don't understand why the serial number has been wiped out.
I have not had the logic board replaced...
But I'm not alone to have this same problem with an original logic board...
Very interesting link, and I thank you for posting it. The Mac mini's owner did replace the drive which I can understand causing this problem.
You may want to think about using Skype instead of Facetime as a work around. However, if most of your contacts are using Facetime, I can understand why you would not want to.
I have exactly the same problem. I sign-on correctly, and that is accepted, then I try to proceed with Facetime startup and fails, and returns to authentication, with "The server encountered an error processing registration. Please try again later."
I have replaced the motherboard in my late 2006 IMac, and it has no serial number, never had one for the NEW motherboard. Facetime is the only thing that seems to kick a fit because of it. My IPhone can Facetime just fine, using my same ID. No problems, so it's not my ID, and it is not a public Apple Server problem. Has to be something like a computer hardware ID problem (something that should be anonymous).
So while everything is fine in Apple land, they made the authentication system too picky, for data that should be anonymous. Since Facetime cannot be installed on something other than a Apple product, you have to wonder what they were thinking. I have been a non-certified Apple tech in my community for more than 10-years. I've never seen anything like this. It is annoying. What's worse, for those rare cases where people manage to build a FrankenMac, since there is a substitute for Facetime, incommon usage (namely Skype); where's the big whoop about the serial number. Sheesh!
I meet the problem since I brought a second hand macbook air 2012 with Yosemite 10.10.2. I don't know why it is missing the serial number but I can't login to FaceTime and iMessage. I looked up a lot of solution on the Internet but no one is useful, do you have any tools can help me to love this situation? Thank you very much!