Hey man!

Sorry to be the guy to ruin the "Solved" tag, in the comment below, but...

14:25 [Error] Failed to call hook 'CanBuild' on plugin 'EntityLimit v2.1.4' (NotImplementedException: The method or operation is not implemented.)
  at System.Globalization.CompareInfo.IndexOfCore (System.String source, System.String target, System.Int32 startIndex, System.Int32 count, System.Globalization.CompareOptions options, System.Int32* matchLengthPtr) [0x00006] in <47fc8c70fa834cbf8141d7c1a7589125>:0 
  at System.Globalization.CompareInfo.IndexOf (System.String source, System.String value, System.Int32 startIndex, System.Int32 count, System.Globalization.CompareOptions options, System.Int32* matchLengthPtr) [0x00071] in <47fc8c70fa834cbf8141d7c1a7589125>:0 
  at System.String.ReplaceCore (System.String oldValue, System.String newValue, System.Globalization.CultureInfo culture, System.Globalization.CompareOptions options) [0x0005d] in <47fc8c70fa834cbf8141d7c1a7589125>:0 
  at System.String.Replace (System.String oldValue, System.String newValue, System.StringComparison comparisonType) [0x00055] in <47fc8c70fa834cbf8141d7c1a7589125>:0 
  at Oxide.Plugins.EntityLimit.ReplaceArgs (System.String message, System.Collections.Generic.Dictionary`2[TKey,TValue] args) [0x0007e] in <c82c8b86c0f4493aa53f3c0191b825d0>:0 
  at Oxide.Plugins.EntityLimit.GetMessage (Oxide.Plugins.EntityLimit+MessageType key, System.String playerID, System.Object[] args) [0x00020] in <c82c8b86c0f4493aa53f3c0191b825d0>:0 
  at Oxide.Plugins.EntityLimit.SendMessage (System.Object receiver, Oxide.Plugins.EntityLimit+MessageType key, System.Object[] args) [0x00013] in <c82c8b86c0f4493aa53f3c0191b825d0>:0 
  at Oxide.Plugins.EntityLimit.CheckBuild (BasePlayer player, System.String fullName) [0x002d2] in <c82c8b86c0f4493aa53f3c0191b825d0>:0 
  at Oxide.Plugins.EntityLimit.CanBuild (Planner planner, Construction entity, Construction+Target target) [0x00007] in <c82c8b86c0f4493aa53f3c0191b825d0>:0 
  at Oxide.Plugins.EntityLimit.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x001db] in <c82c8b86c0f4493aa53f3c0191b825d0>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <cd9a02fd331347bd82d550bb1a9c8e9f>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <b76ec77c47d1449e92b2baab8603843d>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <b76ec77c47d1449e92b2baab8603843d>:0 

I've implemented a fix, but wasn't able to get that error. If it re-occurs, please note what was being done when the error occurred, and include a list of plugins so I can replicate your server environment to test. 

Thank you! Not just for doing this, but allotting some of your electric time to this! 

No errors in the last 3 hours, but I will keep an eye out for the error over the weekend as the servers get more players. 

Sweet. Yeah, couldn't do my day job without a petrol-powered generator. Ironic, since I work for a Solar company.