DOWNGRADE FROM BIG SUR TO CATALINA

EXTERNAL HARD DRIVE NOT VISIBLE IN FINDER

Just went through a bit of a fiasco after downloading MacOS Big Sur a bit pre-maturely. After trying to revert/downgrade back to Catalina I discovered that somewhere along the way my external hard drive was wiped. It may have been due to me specifying for Big Sur to install on the external since my local drive didn’t have the space for it. At that point I think it may have reformatted it for some reason. Either way to get back to Catalina it was easier than anticipated thankfully. All I had to do was reboot in recovery mode(hold command + r once you hear the reboot noise). Then a window should pop up with I think 4 different options. You can access the disk utility from there and there was also an option to “Reinstall MacOs Catalina”. I selected this and after reinstalling my old user account showed up with all of my applications, files, and preferences as they were. However this is when I also discovered my external was wiped and all my files had been replaced with my Big Sur update files and user account files. Thankfully though I did have a full backup of my files on backblaze, which I’m currently downloading - this does take a while though as you are limited in what you can download without being charged and I’d rather not wait 2 weeks for a hard drive to be delivered and pay shipping and taxes on it. All that said, in the future I would definitely recommend using Time Machine on a separate external drive. This would have saved me a ton of time.

SOLUTION

While doing this I also ran into an issue where my external stopped showing up in the finder(on the left underneath “locations”). At some point two separate volume mounts attached themselves to my external - one named “update” and the other was just some rand assortment of characters I think. They were both hidden and not taking up any space, so I just deleted them by right clicking them in the disk utility app and then selecting delete. Once I did this my external started showing up in the finder again.

Originally posted: November 21, 2020