My new external hard drive is WD My Passport for Mac - 4 TB. My macOS is Monterey. I am getting the following message:
If you upgraded to macOS Monterey on a Mac, your existing backups are not upgraded. New backups that are created can be used only on macOS Big Sur or later.
What does it mean that my existing backups are not upgraded? Do I need to purchase a different external hard drive?
iMac Line (2012 and Later)
If this is a "new" (empty) external drive for Time Machine, just make sure it is formatted as GUID - APFS and then designate it for use in Time Machine in the Time Machine Preferences.
If there were old backups already on the external drive, you can continue using it (don't reformat it to preserve what is already on it) but the old backups will remain in an older format, but can still be used. But the newer backups created under Big Sur can only be accessed under Big Sur or later. A computer running an older MacOS won't be able to access those backups.
If this is a "new" (empty) external drive for Time Machine, just make sure it is formatted as GUID - APFS and then designate it for use in Time Machine in the Time Machine Preferences.
If there were old backups already on the external drive, you can continue using it (don't reformat it to preserve what is already on it) but the old backups will remain in an older format, but can still be used. But the newer backups created under Big Sur can only be accessed under Big Sur or later. A computer running an older MacOS won't be able to access those backups.
Thanks for your help! It worked.
Create a Time Machine backup
