Using Time Machine for Backup on Old OS Version

Question

Tomorrow, I am getting the battery replaced on my early 2015 macbook air. As there is a chance of data loss, I plan on using "time machine" to make a back up on an external drive beforehand. I am currently using macOS Catalina. If my disk gets completely erased and I have to re-install macOS, potentially a newer version, will I still be able to restore my data from the backup made in Catalina, or should I update my computer beforehand? If I update, I will have Monterey, (edit: it turns out that Ventura is not yet the current version, so no cause for concern there). I would rather not update if not necessary out of concern that the newer versions may not run as smoothly on my old hardware, and if "time machine" would not work either way then I am seeking an alternative that would work in the event of total data loss on this computer.

Answer 1

This general advice:

You should be able to restore from a Catalina backup with Catalina or any more recent version of macOS (e.g. Monterey). But, it is always most trouble free to restore with same version as that of the Time Machine backup. So I recommend to either:

• Restore with Catalina and use your current backup. You may need to use a bootable USB flash drive to install Catalina.
• Update to Monterey first and make a Time Machine backup. Restore by installing Monterey and recovering from the most recent Monterey backup.

Before any upgrade, make sure that your applications will run with the newer macOS - or have replacements.

When you do upgrade to Monterey, consider starting Time Machine on a new backup disk. I say this because Time Machine now uses APFS disk format which is much more robust for backup.

In any event, keep your old Time Machine backups until you are sure you don't need them.