I have a Mid 2011 iMac currently running MacOS 10.12 Sierra. It’s not my main machine, but I would like to install 10.13 on it.
Updating starts smoothly enough, but when it comes to restarting, I get the following message:
macOS could not be installed on your computer An error occurred while verifying firmware.
I understand that my Mac is on the edge, but I read that any machine which supports 10.12 will also support 10.13
The iMac is running from an external SSD, due to a problem with the logic board, so I know that I have some problems. The iMac no longer boots from the internal drive (or recognises the DVD), but still works otherwise.
However, the problems don’t seem to be invove the actual firmware, and the iMac is happily running 10.12.
What does this message mean, and can it be resolved?