After updating to Catalina, my iMac gets stuck at 'Preparing Bakckup' in Time Machine - and won't back up. It did it once after the OS update, but won't do it again. I've ejected the disk and restarted several times.
Any ideas?
iMac 27″, macOS 10.15
I suggest starting with this support article: If a Time Machine backup takes longer than you expect - Apple Support
You may also find this article helpful: What to Do When Time Machine Is Stuck on "Preparing Backup" - Lifewire
Thank you for those pointers - really helpful. I ran Disk Utility on it, and turned off and on a couple of times, and now it is doing a long 4 hour back up - the disk must have needed to be rebuilt to connect to the new OS. But at least something is happening now!
Time Machine getting stuck at 'preparing backup' after OS update to Catalina
