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I have an iMac running Big Sur but I want to install Catalina on an external drive so that I can use software that is not compatible with Big Sur. Catalina installer is "too old" to run on Big Sur.
iMac 21.5″ 4K, macOS 11.1
Howdy,
How new is your iMac? If your iMac came with Big Sur you won't be able to install and run an earlier macOS.
If your iMac came with Catalina or earlier, please check out:
How to get old versions of macOS
which has information on checking compatibility, backing up, downloading and installing the earlier OS.
example:
Safari uses these links to find the old installers in the App Store. After downloading from the App Store, the installer opens automatically.
Take care,
ivan
Howdy,
How new is your iMac? If your iMac came with Big Sur you won't be able to install and run an earlier macOS.
If your iMac came with Catalina or earlier, please check out:
How to get old versions of macOS
which has information on checking compatibility, backing up, downloading and installing the earlier OS.
example:
Safari uses these links to find the old installers in the App Store. After downloading from the App Store, the installer opens automatically.
Take care,
ivan
Which iMac are you using?
Try booting into macOS Recovery and installing your original macOS from there (to your external drive). Then if needed, you could update to Catalina.
ivan
I already have Catalina Installer in my Applications folder. It will not run in Big Sur. I have created a bootable installer on a hard drive and run from there but mac os utilities eventually opens but mouse & keyboard do now work! Any other suggestions?
I have managed to resolve the problem by connecting a usb mouse to install Catalina to external drive.
What's stopping you?
As I said earlier, Catalina installer "too old" to run on Big Sur therefore I cannot choose the external drive for install. Using bootable installer method also does not work.
You are not going to run it on Big Sur.
Download it. Move it to the external and install it there.
Great. Thanks for letting us (all) know what worked for you!
I am using big sur and want to run Catalina on an external hard dri
