This is what I’m also confused on. I unfortunately don’t know how to get a backup of all my files and I don’t have access to my desktop because my computer won’t log in. I don’t know if all my data is in the regular HD or the HD data. I’ve even tried trying to reinstall then os but this new update has taken over most of my storage and it’s telling me now that I can’t because my storage it too full. I don’t know how to remove things on my storage with safemode not working and me not having access to login in since it’s stuck on the Apple logo
have since rectified the issue.
You need to mount the hard disk and the data hard disk in disk utility from recovery mode.
And attach an external SSD.
Creating a backup:
Open terminal in recovery and type ditto "/Volumes/<Macintosh HD>/users/<your username>" "/Volumes/<External Disk>/<a folder name>", replacing <Macintosh HD> & <External Disk> with the names of them in the disk utility, <your username> with the name of your user folder, and <a folder name> with the name of a folder that exists on the external disk. This folder can be created by typing into the terminal:
cd "/Volumes/<external disk>"
mkdir <folder name>
Then you need to type
ditto "/Volumes/<Macintosh HD>/Library/Extensions" "/Volumes/<External Disk>/<another folder name>"
rm -rf "/Volumes/<Macintosh HD>/Library/Extensions"
cd "/Volumes/<Macintosh HD>/Library/"
As by removing (but first backing up) kernal extensions, you can use the Mac again.
You will enter your login password, it will hang for a few moments then proceed to going back to the software update.
Hope this helps everyone!
Silly question but you mentioned SSD. Is it necessary or can it be any external hard drive? Does it need to be formatted any particular way? Thank you
Had similar issue where my mac crashed on login after installing Catalina. Your solution with removing Extenstions folder worked for me. I was able to login and proceed the installation. Thank you so much for posting!