I recently had to re-format and re-partition my harddrive. I set up four partitions: /; swap; /home; and /home/backup1.
After reinstalling Ubuntu-Mate, I restored all my documents to my /home folder from another backup.
Trying to use Unison to backup my /home folder to my /home/backup1 folder, I continually got the following error message for every folder I was backing up:
Checking folder permissions for /home/backup1 using sudo caja, I found that the owner and group for this folder were both set to root. I easily changed this setting to jim and now Unison is working like a breeze.
If any of you are having problems with Unison, I would suggest that the first thing you do is to check the folder permissions for the drive or folder you are trying to backup to.
I hope this helps someone.
My thanks to Steve Cook for his help with this.