After updating the plugin with v2.3.0 and running update I am getting the following error when I type /shop in chat. It referance rustcord? The GUI fails to open.

Failed to call hook 'IOnPlayerCommand' on plugin 'RustCore v2.0.5297' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000fb] in <9882f28dc2204b4dba514a9ad18f5042>:0
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <9882f28dc2204b4dba514a9ad18f5042>:0

Did you run the update command? As stated in the update notes

Yes I did run Update like the directions said.

Try re-uploading the cs file ( don't use FileZilla ) 

I redownloaded the plugin and installed it. (My server is run on a compter in my office) and got the same error. I then delete all GUIShoip files from the plugin, Data  and config. I reinstalled it from scratch and logged in ran /update and it seems to be working. I was then able to put in my back up config file and it now seems to be working again. (I was worried that I had lost hours of work).

Update: I ended up deleteing the old config file. It it was not working correctly. So back to editing it again. The plus side I learned alot. (Wish list idea) Maybe add an Admin menu GUI like Stack Modifier.

Thanks again for your help!!

If you still have the old config file please send it, I'll take a look at it.
My discord id is @ Khan#8615