(NullReferenceException: Object reference not set to an instance of an object)
at Oxide.Plugins.Notifier.InitializePlayer (BasePlayer player, System.Boolean joined) [0x00027] in <94d9656861c2416e8d292977a6a87fd1>:0
at Oxide.Plugins.Notifier.Loaded () [0x00053] in <94d9656861c2416e8d292977a6a87fd1>:0
at Oxide.Plugins.Notifier.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00467] in <94d9656861c2416e8d292977a6a87fd1>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <1e2d7ad0801a4037ab6a24578c814b54>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <1fe782f4b27a43ae85d29ebb2d56c007>:0
at Oxide.Plugins.CSharpPlugin.HandleAddedToManager (Oxide.Core.Plugins.PluginManager manager) [0x0006e] in <1e2d7ad0801a4037ab6a24578c814b54>:0

This error is comming out of no where, plugin was running fine untill a few weeks ago :(.

I'd suggest contacting the author of that plugin, which isn't hosted here.

Issue is the plugin isn't being maintained by anyone any more, its outdated & i managed to keep it alive myself. Some of my servers can run it perfectly, but other gives this msg...

You'd need to add some null checks to see where it is null and then go from there.