19:08 [Error] Failed to call hook 'cmdTrade' on plugin 'Trade v1.2.41' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.Trade.cmdTrade (BasePlayer player, System.String command, System.String[] args) [0x0018c] in <8e25f2beb0ee489299378e574933437f>:0

  at Oxide.Plugins.Trade.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00b08] in <8e25f2beb0ee489299378e574933437f>:0

Essentially the plugin is using a hook that is no longer in Ignore. Just open Trade.cs and edit line 513 from

var IsIgnored = Ignore.Call ("IsIgnored", player.UserIDString, targetPlayer.UserIDString);​

to

var IsIgnored = Ignore.Call ("IsIgnoredBy", player.UserIDString, targetPlayer.UserIDString);​

Doesn't work @AnExiledGod

Failed to call hook 'cmdTrade' on plugin 'Trade v1.2.42' (InvalidCastException: Specified cast is not valid.)
  at Oxide.Plugins.Trade.cmdTrade (BasePlayer player, System.String command, System.String[] args) [0x0018c] in <55409bd8768e48788440296bdd79cdfd>:0
  at Oxide.Plugins.Trade.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00b08] in <55409bd8768e48788440296bdd79cdfd>:0
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <9affce1cd15c4ec183941adef8db1722>:0
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <4452f821def6406d834e4149849fe7ea>:0
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <4452f821def6406d834e4149849fe7ea>:0

Aww, alright. I'll take another look today and do extensive testing before I pass it on. Sorry about that!

When I installed this plugin the Trade plugin broke.
would recieve following error:

 Failed to call hook 'cmdTrade' on plugin 'Trade v1.2.4' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.Trade.cmdTrade (BasePlayer player, System.String command, System.String[] args) [0x0018c] in <b5d753bc327c41a7bf257b0d9245f844>:0 
  at Oxide.Plugins.Trade.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00b08] in <b5d753bc327c41a7bf257b0d9245f844>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <9affce1cd15c4ec183941adef8db1722>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <4452f821def6406d834e4149849fe7ea>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <4452f821def6406d834e4149849fe7ea>:0​

Removing Ignore plugin trade works with no errors.
Issue with this plugin or do I need to also make a post on the Trade plugin support area?
Thanks

Merged post

Thanks for the "merge" @Wulf
I guess I should have checked here first. Looks like i need to update trade plugin.