by skibble 11 hours ago
I have set up Time Machine backups for literally hundreds, if not thousands of people in a support role over many years and have hardly ever witnessed this happening. It's one thing to say you may have had to do this once or twice in a decade or the like, but every few months is ridiculous and speaks to some other underlying issue with your setup, like a quietly failing drive or bad cable, etc.
I'm not one of these 'it hasn't happened to me, ergo it's impossible people'. I completely think that many of the design elements of Tahoe are a horrendous regression versus even Sequoia, but I think asserting that Time Machine is completely broken in the shipping version of macOS is a bold statement that deserves a bit of pushback, even among the fire raging in a lot of other places in macOS!
This is a very common error case, more common with storing the backup on a network share (Wifi / Ethernet doesn't matter). If you look for "Time Machine must erase your existing backup history and start a new backup to correct this." you'll find a lot of references for this problem.
To be clear, I'm not saying it's Tahoe related, it has been there for many years.
Did you only set up Time Machine? Or did you continue supporting all those users for years and years. If the issue is that eventually the backup store becomes corrupted then you may not see it at all if you're only setting up backups but never dealing with users who actually need to restore something from backup years later.
For me, it's backing up over a network share. My Synology NAS works perfectly and flawlessly for literally everything else. It's RAID 1. It supports Time Machine. But somehow it would get corrupted every few months and I'd have to start it all over.
Tons of people complain about this. I suspect it's some subtle bug with sparse bundles and SMB.