by Ken Task.
One other idea ...
The file name:
backup-moodle2-course-77-[100_%_xxx_xxx_xxx]_1-_fundamental_(feb._28_-_may_9_)-20170628-1354-nu.mbz
That's a doozy of a course title and/or shortname.
Moosh nor Moodle Web based restore routine doesn't care about file names, but contained in the backup there is data for course fullname and shortname .... just like above.
This wouldn't be hard to try:
un gzip the backup file.
In the moodle_backup.xml file, shorten the 'shortname' taking out characters like % and ().
Save the xml file.
Repackage the backup (gzip with .mbz extension) ... this time give it backuptest1.mbz as a name.
Try to restore.
Since the backups contain no users, am about to suggest you upload the .mbz file where I can acquire it so I can un-archive and inspect the contents ... as well as attempt restores on a similar machine.
'spirit of sharing', Ken