by Ken Task.
Your on leading edge (bleeding edge) moodle version which is now: 4.5.3+
fgrep '$release' version.php from moodlecode root.
In admin/cli/ there is a script called fix_course_sequence.php
suggest you run it.
Also:
https://docs.moodle.org/405/en/Course_restore
Your 4.5 needs to have all the same addons/plugins that are contained in the backup file if the backup file came from another server.
One can restore course backups from CLI ... again look in moodlecode/admin/cli/ for restore_backup.php
Might also consult Moodle Tracker for issues and resolutions or status of reported issues.
https://tracker.moodle.org/browse/MDL-81189?jql=project%20%3D%20MDL%20AND%20text%20~%204.5
'SoS', Ken