Time Machine oddity

KaneHau wrote:

I recently sent my MacBook Pro into Apple for repair. As part of the repair they wiped my drive clean and installed Catalina 10.15.4.

Prior to shipping it to Apple, I did a full backup to Time Machine. I was running Catalina 10.15.4 and have done numerous backups since installing Catalina.

Upon receiving the repaired laptop back from Apple, I did a full Time Machine restore.

While my personal files were restored properly (eg., changes I had made the day of the backup were indeed restored) - the restore installed Sierra, rather than Catalina.

What happened for that to occur? How do I ensure that future backups are backing up Catalina.

I was totally blown away by this - it has to be a bug in Time Machine and/or Catalina.

As a note, this Time Machine backup has been used for several years, so it did indeed have Sierra on it, but it should have also had Catalina on it and restored it, not Sierra.

Any suggestions would be appreciated.

Select your Time Machine backup, then click Continue.

If you're asked to choose from a list of backups organized by date and time, choose a backup and click

Restore your Mac from a backup - Apple Support

3-2-1 Backup Strategy: three copies of your data, two different methods, and one offsite.

Boot clone https://discussions.apple.com/docs/DOC-10081

How to use Time Machine to back up or restore your Mac: https://support.apple.com/en-us/HT201250

Use DiskUtility Restore feature https://support.apple.com/guide/disk-utility/restore-a-disk-dskutl14062/mac

note: >System Preferences>Security & Privacy >Privacy>Full Disk Access

unlock the padlock, press the + button and add Disk Utility

Yes he screwed up booted in Recovery Mode and installed the first version of Mac OS installed on your system and then used Migration Assistant and moved your personal files to it!