Are any of you using Hackintosh or the Chimera bootloader on your Macs?
If so either install Clover bootloader (an EFI-based bootloader) or uninstall Chimera.
If you install Clover bootloader, you will need to get Chameleon Wizard as well to generate a serial number.
After installing Clover, go into /EFI and open up the config.plist file with TextEdit
Using Chameleon Wizard generate a 11-or-12 digit serial number for the appropriate SMBIOS and put it in there. Add some random numbers on top of the 11-or-12 digit serial number and make it so it is a 17-digit serial number, Clover uses 17-digit serial numbers.
A part of my config.plist looks like this so change the part where it has the serial number on it
<key>RtVariables</key>
<dict>
<key>MLB</key>
<string>C02JK967DHJT21412</string>
</dict>
<key>SMBIOS</key>
<dict>
<key>ProductName</key>
<string>iMac12,1</string>
</dict>
This is a fix for those on a Hackintosh or using the Chimera or Chameleon bootloader.