Unable to make backup using Time Machine
iMac Retina 5k, 27-inch, late 2015
Catalina 10.15.1
Lately I checked Time Machine and realized that my last backup was 2 months old. I had used Time Machine Editor to make the incremental backups once a day.
I erased the external HDD and started a full backup. After a few unsuccessful tries I assumed an HDD problem and got myself a new HDD. Same problem. After at least 10 hours the backup is stuck at around 730GB of 900GB. The "remaining time" goes up and the backup never finishes. I swapped the USB port but again same result.