Hello, someone have got the same issue here Sauvegarde Dolibarr par yunohost impossible
The script backup must have a misconfiguration on the precedent version, I am really sorry.
You can fix it editing the file manually, connected with ssh using nano editor
sudo nano /etc/yunohost/apps/dolibarr/scripts/backup
this line here must be edited
# Check if the group is set
if [ -z "${syncyunohost_main_group}" ]; then
Change it like this
# Check if the group is set
if [ -z "${syncyunohost_main_group:-}" ]; then
To quit the editor nano Ctrl + x and said yes to keep the changes before closing the editor.
Then the backup and so the upgrade should works.