Time Machine not working on Catalina

It hasn't been forever yet 🙂

TM is reporting that it needs to back up 1.73 TB. That's a lot. It's not at all unusual for it to stay in that state for a long time. If there is literally no progress after a full day please write back for additional suggestions.

Lehman College wrote:

I just upgraded from Mojave to Catalina (10.15.7). I have Time Machine working well on Mojave, but now I am having problems.

Please describe those problems.

The formatting of the drive is Mac OS Extended (Journaled) and it checks out when I run First Aid.

If you can't back up or restore your Mac using Time Machine - Apple Support suggests running Disk First Aid on the source volume as well:

• To check an external drive connected to your Mac, open Disk Utility from the Utilities folder of your Applications folder. Then use the First Aid feature in Disk Utility to verify your disk. Do this for your startup disk as well.