Since updating OS from Sierra to Big sur my backup is not working in Time Machine. It just displays backup error after a couple of minutes of preparing backup and fails. Any ideas?
iMac 27″, macOS 11.5
That's a massive leap in operating system versions. You might need to get another new backup drive if you wish to keep your Sierra backup history intact. Or reformat the backup drive with Disk Utility and APFS and then make it your Time Machine drive moving forward. There were many changes to macOS along the way including a new file system (APFS) and changes to Time Machine:
macOS Sierra 10.12
macOS High Sierra 10.13
macOS Mojave 10.14
macOS Big Sur 11.6.3
After discussions with Apple Support Team I tried a Force Restart of my Mac and attempted running the backup again. This worked successfully although the backup took a lot longer than previously
That makes sense, it had to literally copy the entire internal disk over because most everything changed radically since Sierra.
Time machine backup error after updating from Sierra 10.12 to Big Sur
