Since 1.20, there's a persistent server crash issue when players with rifle slings are loaded from the database.
To further clarify, a "weapon sling" in this regard is a Clothing object with slots that Rifles or other items can be attached to, which is worn in either the Shoulder or Melee slot.
There are multiple mods which provide weapon slings, all of which seem to be affected and therefore the suspicion is that loading items and attaching them to the relevant slots is causing the crash, rather than a P3D issue.
These crashes seem to occur primarily shortly after server boot, and will typically happen to the same player multiple times in a row.