🐛 Root Cause Found & Fixed:
- Error occurred when accessing backup_job.created_by where the referenced user was deleted
- Django was trying to fetch a User object that no longer exists
- Changed to use backup_job.created_by_id instead of backup_job.created_by
- This avoids the foreign key lookup that was causing the 'User matching query does not exist' error
✅ Backup cancellation now works even when:
- Original creator user has been deleted from the database
- Foreign key relationship is broken but ID is still stored
The backup job can now be cancelled without triggering user lookup errors.