Reverting to Mojave

[rexanders]

I have an iMac and a Macbook Pro.

When Catalina was released, my iMac was in for repair. I upgraded the Macbook and, inevitably, lost the use of a lot of 32bit programs.

Now my iMac runs Mojave and the Macbook runs Catalina. Ideally, I would like this to be the other way round.

Presumably, I can clear the Macbook of it's operating system and then do a clean reinstall using the iMac and migration assistant so that the Macbook runs on Mojave and then then upgrade the iMac to Catalina.

Could somebody please briefly talk me through this process

 

[ferrarr]

As long as you have all your data backed up, you should be good to go.

On the iMac, you should create a Mojave bootable USB installer, How to create a bootable installer for macOS - Apple Support. Then you can boot the MBP from the USB, erase/format/wipe the startup drive. Then install Mojave and copy what you need to it.

When you are booted from the Mojave USB, use Disk Utility and make sure under the View menu, "All devices" is selected.