To use this method, you must have made a Time Machine backup prior to the OS X 10.9 upgrade. Users who upgrade to OS X Mavericks may encounter issues with their new operating system. Follow the prompts to reinstall macOS Mojave. Quit Disk Utility and choose Reinstall macOS from the macOS Utilities window. In the pop-up window, choose Mac OS Extended (Journaled) from the Format drop-down menu, then click the Erase button. Select your startup disk from the left sidebar, then click the Erase button. When the macOS Utilities window appears, choose Disk Utility. Boot into macOS Recovery by holding down Command+R while your Mac is booting up. Once you have a backup, follow these steps: 1. This will require you to have a backup of your data, as all data on your hard drive will be erased. To downgrade from macOS Catalina to macOS Mojave, you will need to erase your hard drive and reinstall macOS Mojave. How Do I Downgrade To Osx Mavericks? Credit: OS X Daily What would be your recommendation on whether I should try to work this out on my own due to the fact that I’ve wasted so much time already – days, in fact – that I’ve had no results at all? I have a mid-2012 2.9ghz i7 machine with 16 gb ram, 1tb SSD drive, and was until recently running Mavericks 10.9.5 on it. The grading is down from High Sierra to Mavericks. Finally, you can install Mavericks on your Mac. Then, you need to boot your Mac from that drive and format your Mac’s hard drive. First, you need to create a bootable Mavericks installer on a USB drive or SD card. Downgrading your Mac from macOS High Sierra to Mavericks is easy and only takes a few steps.

Update from sierra to catalina