MacBook Pro Serial Number Not Available Today, I opened up an application to see check how my battery is going along, health, etc. It said that my Mac had an unknown manufacture date and no serial. I opened up About This Mac, and saw that for some reason, it says my serial number is "Unavailable", and it doesn't show the exact model of my mac (It just shows "MacBook Pro" instead of "MacBook Pro, Retina Late 2013" like it used to, even when I click on it)

I do have the serial number written down, and checked my warranty with Apple. I do have a valid purchase date, and Apple Care for 1 more year. 

I have had the display replaced under warranty a few months ago, but I am pretty sure that that did not do it.
The best way is you should ask Apple to fix this.

If you wanna DIY (WARNING: at your own risk), with a tool named Blank Board Serializer (ver 1.1 part number 063-7137, please google it if you want), you can set your serial number onto your Apple computer board. There are some step by step video that should be found easily on YouTube.

Steps:


Burn the BBS disk image to a CD/USB.
Boot the compute and press the option key (i.e. the Boot Picker).
Insert the CD/USB and select it for booting.
Once the Blank Board Serializer has started, follow on-screen instructions.