Problem Installing Catalina on MacBook Air
So yesterday I attempted to install Catalina on my 2018 MacBook Air. It didn't go well. I did the usual backups prior to the installation. The install process went through the normal process until the end when I received the following screen about not being able to save "opt" in the folder Macintosh HD-Data. Click restart to try the install again. I attempted the install again and got to the same point.
I called Apple to see if there was something I missed or how to get out of this loop. Their recommendation was to go back to Mojave from my clone. He told me to wait until the next update and try again. While I was surprised at that comment, that is what I decided to do.
However, I ran into trouble restoring my Carbon Copy Cloner clone because I think I had both a Macintosh HD and a Macintosh HD Data APFS volumes. I'm assuming those two volumes were created from the Catalina attempt. The restore, while it says it completed without error, did not allow me to login in. When I gave it the password, there was a quick whoosh sound and then the mac rebooted.
What I did next was start up from the clone, go into Disk Utility and delete both apfs volumes, Macintosh HD and Macintosh HD Data. Then I created a new apfs volume called Macintosh HD.
I was then able to successfully restore my clone and I'm back running on Mojave.
Has anyone else run into this problem? Anyone have any advice on what happened or where to go next?
That may be your problem. Either create /private/opt or remove the symlink before trying again.