time machine verification keeps failing

To get a handle on where the problem is, obtain a low cost external drive and connect it up to your Mac via cable, properly formatted for Time Machine, and try a backup to it. You can simply add the drive as a backup destination, leave your others as they are.

If backup to a cabled external drive works reliably, then that tells you that your Catalina installation and Time Machine software does work. And you should then examine your setup for backing up via WiFi to make sure each element is compatible with Catalina.

If it doesn't work even with a cabled drive, then that means your installation of the MacOS could be corrupted and you may need to take some corrective action there.

CLM-tech wrote:

I found a lot of postings to this question but no real answers. Since updating to Catalina, time machine back ups no longer work. I have to start a new back up constantly and after one or more days the verification fails. Yes it's over wifi but I've backed up the same machine with no problems for years the same way until the update. No I don't use Norton. I've tried backing up to Synology and Capsule and get the same error. I don't want to back up to a USB or over ethernet, I want Time Machine to work that way it should and had for a dozen years. Something with regards to Time Machine is broken with Catalina (and Big Sur). I don't need troubleshooting tips. I need to know if anyone has real and concrete answers of how it is broken and if there is a solution.

Try a different drive.