how to downgrade macOS catalina to mojave
how to downgrade macOS catalina to mojave
iMac 21.5″, macOS 10.15
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Did this iMac come with macOS Catalina installed originally? If so, you will not be able to downgrade it. However, if it did come with an earlier version of macOS (Sierra, High Sierra, or Mojave) and you upgraded it to Catalina, you will still be able to downgrade it.
With that said, and assuming your answer will be the latter, to downgrade from macOS Catalina, will take the following basic steps:
- Backing up your Mac - I suggest making both a Time Machine backup and a cloned-copy of your Mac's system drive with something like, Carbon Copy Cloner, for the latter.
- Creating a Bootable USB installer Disk - To create a bootable installer, you need to have the macOS Mojave installer file downloaded onto your Mac. Ref: https://osxdaily.com/2018/09/29/download-full-macos-mojave-installer/
- Erasing your macOS Catalina Installation. Ref: How to erase your Intel-based Mac - Apple Support
- Installing a "new" macOS Mojave version on your Mac. Ref: How to create a bootable installer for macOS - Apple Support
- Verifying the Install