Backward compatibility
Depends on what you mean by that exactly.
What are the most breaking changes between 5.7 and 6.6 ?
Would restoring a database backup from version 5.7 to a version 6.6 backend cause any problems? I have reviewed the blogs from version 5.8 onwards and have not found any major changes to the database scheme. Therefore, I believe it is safe to upgrade. Please correct me if I'm wrong.
Should be safe.
I am going to upgrade Traccar Server as I am stuck on version 5.7, is there a full backward compatibility? I am planning to upgrade to version 6.6