Time Machine couldn't complete the backup to my external drive. An error occured while preparing the backup. This happened after I erased the drive.
iMac 21.5″ 4K, macOS 13.3
Try booting into Safe Mode according to How to use safe mode on your Mac and try to complete a backup from there. If you're successful in Safe Mode reboot normally and try another backup.
Note: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will assure a successful boot into Safe Mode.
If you're still unsuccessful you can do what I had to a while back when TM couldn't get beyond preparing: erase the TM drive and start over from scratch. This is a good method if you don't have any files on the TM drive that are not on your boot drive that you need.
I tried both methods. When aI reformatted the disc I used APFS. For some reason Time Machine doesn't see the T M drive.
Could the TM external drive be locked, not allowing anything to be copied to it and iso how wo you unlock a drive??
Does Disk Utility see the drive? If it can then reformat it as OS X Extended (journaled) and see if TM can see it. If it can try making a backup to it.
This worked. Thank you for your help!
Time Machine couldn't complete the backup to ext ernal drive. An error occured while preparing the backup.
