Failed to call hook 'CanUseLockedEntity' on plugin 'SharedDoors v1.0.1' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.SharedDoors+RustIOHandler.IsFriend (System.String playerId, System.String playerDoorOwner) [0x00006] in <0d1783308cdf49e189b24788c55e3d40>:0 
  at Oxide.Plugins.SharedDoors+DoorAuthorizer.CanOpenCodeLock (CodeLock door, BasePlayer player) [0x00096] in <0d1783308cdf49e189b24788c55e3d40>:0 
  at Oxide.Plugins.SharedDoors+DoorAuthorizer.CanOpen () [0x00036] in <0d1783308cdf49e189b24788c55e3d40>:0 
  at Oxide.Plugins.SharedDoors.CanUseLockedEntity (BasePlayer player, BaseLock door) [0x00088] in <0d1783308cdf49e189b24788c55e3d40>:0 
  at Oxide.Plugins.SharedDoors.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00261] in <0d1783308cdf49e189b24788c55e3d40>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <33f7c42a56934dae8ec04b11017dce31>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <33287985591c40d6983f0b8f0e915565>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <33287985591c40d6983f0b8f0e915565>:0

(22:52:41) | Failed to call hook 'CanUseLockedEntity' on plugin 'SharedDoors v1.0.1' (NullReferenceException: Object reference not set to an instance of an object)
at Oxide.Plugins.SharedDoors+RustIOHandler.IsFriend (System.String playerId, System.String playerDoorOwner) [0x00006] in <3825e0649b1f436596486e2864cb9194>:0
at Oxide.Plugins.SharedDoors+DoorAuthorizer.CanOpenCodeLock (CodeLock door, BasePlayer player) [0x00096] in <3825e0649b1f436596486e2864cb9194>:0
at Oxide.Plugins.SharedDoors+DoorAuthorizer.CanOpen () [0x00036] in <3825e0649b1f436596486e2864cb9194>:0
at Oxide.Plugins.SharedDoors.CanUseLockedEntity (BasePlayer player, BaseLock door) [0x00088] in <3825e0649b1f436596486e2864cb9194>:0
at Oxide.Plugins.SharedDoors.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00261] in <3825e0649b1f436596486e2864cb9194>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <8a646463979e4a1d9c0e2f1298e9483f>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <953329caf7d943cc9eca5c8b4b890c98>:0
at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <953329caf7d943cc9eca5c8b4b890c98>:0

A little late to the party there ! Deleted the plugin is the only fix!! 

Use this plugin instead

https://umod.org/plugins/automatic-authorization

This error happens each time someone who is authed on TC tries to open/close a locked door of a player who they are not friends with on steam. Any chance you have time to look for a fix? Because I prefer this plugin as opposed to the one listed above.