I installed Catalina on my 2019 MacBook Air. I want to uninstall it and reinstall Mohave, but I only have some data backed up, not the whole computer. I'm backing up with Time Machine now (in Catalina), but when I use Time Machine to replace everything after uninstalling Catalina and reinstalling Mohave (from a Mohave bootable drive I'll create), won't that cause problems -- since the backup will have all the Catalina stuff?
... when I use Time Machine to replace everything after uninstalling Catalina and reinstalling Mohave ...
Don't do that. A Time Machine backup contains the complete contents of its source volume. If you were to "restore everything" then the contents of the target system will be completely replaced with the contents of its backup.
Time Machine contains backups of everything up to and including files created or modified within the last hour of using your Mac. You wrote that you don't want to lose those files, so create a Time Machine backup of the existing system. Then, erase the source, install or restore whatever macOS version you wish to install or restore, and finally migrate or selectively restore the recently created or modified files you need.
Refer to Use Time Machine to restore deleted files or older files.
... when I use Time Machine to replace everything after uninstalling Catalina and reinstalling Mohave ...
Don't do that. A Time Machine backup contains the complete contents of its source volume. If you were to "restore everything" then the contents of the target system will be completely replaced with the contents of its backup.
Time Machine contains backups of everything up to and including files created or modified within the last hour of using your Mac. You wrote that you don't want to lose those files, so create a Time Machine backup of the existing system. Then, erase the source, install or restore whatever macOS version you wish to install or restore, and finally migrate or selectively restore the recently created or modified files you need.
Refer to Use Time Machine to restore deleted files or older files.
Having a Time Machine backup is always advantageous. It will contain all that Mac's contents including files and other User Account data you may have forgotten about or otherwise neglected to back up.
I'm afraid this doesn't answer my question, which is:
Since my backup was made only after I installed Catalina, will restoring everything with Time Machine be a problem when I reinstall Mohave? Won't my backup have Catalina-related files that will interfere with Mohave?
OK. I'm clear now. Thank you.
👍
reinstalling mohave with no pre-Catalina backup
