by Ken Task.
Your screen shot shows asynchronous backup ... that's via GUI, and you, the user, put the backup process into a background process - which then does not show the entire progress of the backup. Instead of clicking links to go onto other in the Moodle, stay on that screen until you see it report success. (moosh does not do that)
The very last thing that backup process does is to 'copy' - note that's 'copy' - the backup.mbz file in the build directory (moodledata/temp/backup/longdirectoryname/backup.mbz) to the destination directory for backups ... found in backup preferences setup.
Suggest going into moodledata/temp/backup/ directory with a file browser and then into any longdirectoryname (bunch of letters and numbers) to see what is in them. If you see a backup.mbz file and a moodle_backup.xml file present that .mbz file is a valid backup ... what your server could not do for some reason, it to *copy* the file to destination.
In automated backup setup, what is your setting for where to save backups?
You have: 1) Default: Course backup filearea - which is the sea of files in moodledata/filedir/
2) 'Specified Directory for automated backups' which means you must also set the path to that directory (save to) or
3) Course Backup Area AND the specified directory.
which is both places.
There is also what to save .. users/no users, etc.
Culprits on failed *could be* an addon plugin in a course.
Size of course ... if one includes everything, could be a course whose backup is the the Gig range.
You can get a look at all backup files via query of DB:
select filename,filesize,component from mdl_files where filename like '%.mbz';
And there is an addon, All backups, that you consider adding to the 100's of addons your site already has.
As is normal, not one simple thing. :|
'SoS', Ken