I've tried a few times and the outcome is always the same. It downloads the full 12.13Gb and gets stuck there for a couple of hours, then I get an "Installation failed" message.
When I retry, it seems to use some of the previous download (sometimes 3Gb, sometimes 4Gb) and take it from there, to end up the same way.
I'm installing from System Preferences > Software Update.
Try the following:
Initiate the download again but do not continue with the installation when prompted, just quit the installer when the installer asked to chose a disk. Get a USB Flash drive of at least 16 GB and create a bootable installer per this document:
How to create a bootable installer for macOS - Apple Support
The article also tells you how to use it as well.
Before starting the install process, disconnect all attached devices other than display, keyboard. and mouse. Next open disk utility and set it to show all devices:
Then proceed to do First Aid starting with the highest level, the drive itself and work down the list applying First Aid to all.
Once complete, follow the instructions in the article I posted to boot to and install from the external USB installer.
Try the following:
Initiate the download again but do not continue with the installation when prompted, just quit the installer when the installer asked to chose a disk. Get a USB Flash drive of at least 16 GB and create a bootable installer per this document:
How to create a bootable installer for macOS - Apple Support
The article also tells you how to use it as well.
Before starting the install process, disconnect all attached devices other than display, keyboard. and mouse. Next open disk utility and set it to show all devices:
Then proceed to do First Aid starting with the highest level, the drive itself and work down the list applying First Aid to all.
Once complete, follow the instructions in the article I posted to boot to and install from the external USB installer.
You will need at minimum, a Late-2014 Mac mini, and if you are upgrading from Siera (or earlier), 45 GB of available storage, or from High Sierra or later, 35.5 GB of available storage — before commencing the upgrade. Restart the software update after you have met the required minimum available storage.
Don't let Monterey use the Time Machine drive that you used to make the last backup on the previous operating system.
M1 Mac mini won't upgrade to Monterey
