Stuck in vicious upgrade loop
I am in a frustrating upgrade loop that I can't seem to get out of despite trying a lot of things.
The problem started when I attempted to upgrade from Mojave to Catalina...all seemed to be going well until I got to the Catalina install reboot phase, at which point I got an error telling me that I didn't have enough disk space (even though it allowed me to start the process).
Since then, I have tried the following:
- Boot in to recover mode, re-install Mojave. It won't let me do this either, as I only have 4GB remaining and it says it needs an additional 7.4GB.
- I have tried to free up disk space from Terminal window, which is accessible from Utilities in Recovery Mode. No matter what I remove, the amount of free disk space never goes down, which is I suspect due to Time Machine not allowing things to be actually deleted.
- I found some documentation on how to clear up space using the tmutil command line, but this is not available from the command line in recovery mode.
- Tried rebooting in to Safe Mode, which it won't do(just ignores the Shift key on boot). It boots normally and when I log in, it attempts the Catalina upgrade process again, which ends at the same disk space error.
- Tried booting in to Target mode, but it is a MacBook Pro and no matter what cable I try to connect to it (USB-C to USB-C, USB-A to USB-C, USB-B to USB-C), nothing seems to see the disk on the Target Macbook Pro. If I can get in to Target mode, I may be able to free up enough space to allow the upgrade to continue, or the Mojave recovery install.
- Tried zapping PRAM...also does not appear to work although this should have no effect.
Does anyone know of a way from Recovery Mode command line to prevent the Catalina upgrade process from attempting to continue? This would seem to be the most straightforward path, then I can clean up my TIme Machine backups and have enough space to install.
I cannot see any path out of this absent formatting disk at this point, which I really want to avoid. Any help or new ideas would be appreciated.
MacBook Pro