server issue

30.10.2024 01:28:04 [Server Notification] Client uid gfhfgh attempting identification. Name: Veraldur
30.10.2024 01:28:04 [Server Error] Could not load a players inventory. Will ignore.
30.10.2024 01:28:04 [Server Error] Exception: Don't know how to instantiate inventory of class 'xskillshotbar' did you forget to register a mapping?
   at Vintagestory.Common.ClassRegistry.CreateInventory(String inventoryClass, String inventoryId, ICoreAPI api) in VintagestoryLib\Common\ClassRegistry.cs:line 67
   at Vintagestory.Server.ServerWorldPlayerData.Init(ServerMain server) in VintagestoryLib\Server\Models\ServerWorldPlayerData.cs:line 194