I just purchased a 27" iMac with the 10 core/i9 engine and Big Sur, which is without a doubt the worst OS I've used in 30 plus years of Macs. How can I downgrade to Mojave (the last really good OS). I've tried to erase and reinstall to no avail. I've tried to load Mojave from Time Machine to no avail. There has to be a way.
iMac Line (2012 and Later)
No iMac can run an older macOS than it originally shipped with.
see > https://support.apple.com/en-us/HT201686
Basically because the older macOS does not support the newer iMac's hardware.
No iMac can run an older macOS than it originally shipped with.
see > https://support.apple.com/en-us/HT201686
Basically because the older macOS does not support the newer iMac's hardware.
You cannot, Macs cannot have a version of Mac OS installed on it than what it originally shipped with.
What exactly is the problem you are having with Big Sur? Perhaps we can assist.
Sorry, you cannot! The latest model of the 27" iMac only supports macOS Catalina and macOS Big Sur, NOT macOS Mojave.
Jack
You may not have prepared the old Mac so it is current and also may not have migrated properly when you copied so please read on!
Current versions of Mac OS no longer no longer support 32 bit apps. Apple advised you for many years however you have misunderstood or ignored the messages. On your old Mac please update your legacy apps to their 64bit counter part versions. If you find any that cannot be upgraded (the developers of the apps need to do that) then replace them or decide if you really need them. You can use System Information to look at your legacy third party apps to determine which are 32 bit or you can use the Roaring Apps tool to find what you have that is 32 bit.
After upgrading all the legacy apps on the old Mac that you want to keep then it is time to migrate. How you do that is first backup the old Mac using Time Machine. Once you have it backed up then simply execute the steps in Setup Assistant and Migration Assistant and you are done. If you have already started adding stuff to the new Mac then you may want to start over by doing an Erase and install so your migration starts with a clean slate.
****! I was looking forward to using the power of the new iMac, but with Mac OS Mojave. I'm still trying to figure out why I can't copy apps or dox from external HD to my iMac. There are so many apps that, over the years, I've gotten used to. I guess I'll be using my 2013 MacPro desktop far more than I thought. Where can I research how to solve my Big Sur problems...the copying is the biggest. Thanks much.
Downgrade from Big Sur to Mojave
