What to Do If Your Mac is Missing or Forgotten Its Serial Number


For the most part, you can go along just fine with your Mac not knowing its serial number or revision (manufacture year). You can still install programs, log in to the Apple Store, use iMessage with your friends and colleagues, and so on. However, problems may surface over time wherein some services such as iMessage or FaceTime will no longer allow you to log in.

The sample screenshot below shows that the Mac’s Serial Number indicates “Unavailable” which means the Mac has somewhat forgot its serial number for some unknown reason.

However, here are some VERY IMPORTANT reminders you should know before trying to fix this issue on your Mac’s serial number:

  • If you have an Apple warranty for your Mac that is still valid, it’s best to contact Apple Support first hand in order to have the serial number fixed. Performing this method will void any valid warranty your Mac may have.
  • You not only need a valid serial number, but you need a valid serial number for the hardware you will be performing it on. The serial number is NOT transferrable between machines. Therefore this fix is truly for your genuine Apple hardware that has lost it’s serial number along the way on its logic board. You’ll be using the same serial number that the computer originally had when you first purchased it.
  • There is no room for error. You only get one chance at inputting the proper serial number during the “write” phase of the how to. If you mistype any part of it, you’ll likely end up with a non-bootable system. DO NOT PERFORM THIS PROCEDURE IF YOU CANNOT DEAL WITH A NON-WORKING MACHINE.
  • The software that will be used in this article may or may not be for Apple’s internal use only. Be warned not to use this software if you worry regarding the copyright or legal issues that may or may not be involved in running and/or using the said software.
  • Perform this procedure at YOUR OWN RISK. We are not liable for any damage it may cause to your Mac.

Search for Your Serial Number

Upon purchase of your Mac from Apple.com, you’ll get a receipt via email where your device’s serial number is indicated. The box where your Mac came in also has the serial number, which can be found on the card inside the box. Also, the Mac itself has its serial number printed on it. So there’s very little excuse not to have the serial number information of your Mac.

Provide a USB Flash Drive

As part of this procedure, you’ll need to be able to boot off a seconday drive, in which a USB drive is advisable to use. Don’t worry about getting a USB drive with a large storage space since the files are very small in size.

Get the Software

The software to be used is called Blank Board Serializer. The link for this software will not be provided therefore, search it online at your own risk.

After you have understood the risks and have prepared the necessary items to be used, you may now proceed with the steps below:

STEP 1: Format the USB drive with Disk Utility with the FAT filesystem.

STEP 2: Next, unpack the Blank Board Serializer program to your USB drive.

STEP 3: Using the Disk Utility, Restore the unpacked dmg file to your USB drive.

STEP 4: Click Done.

STEP 5: Shut down your Mac.

STEP 6: Reboot your Mac while holding the [option] key.

STEP 7: When presented with various boot devices, choose the EFI USB key.

STEP 8: On the usage agreement, click Accept to proceed.

NOTE: Take note of the warnings mentioned above once more. The next step is very crucial, which means take extra caution in performing it.

STEP 9: Enter your Mac’s serial number WITHOUT ERROR.

NOTE: Be mindful that zeros (0) and O’s look very similar.

STEP 10: Hit [Enter] when you’re done.

STEP 11: Click Yes on each following prompt.

STEP 12: Click Proceed.

STEP 13: Click Restart.

This completes the risky method of reviving your Mac’s serial number. You may go back to the Overview screen to check if the serial number is now showing correctly as shown below.

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