Starting the server, the following error appears on the console (red letters):

[Automated Events] Killing a CargoShip
Failed to call hook 'OnEntityKill' on plugin 'IOCore v1.0.1' (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
Failed to call hook 'OnEntityKill' on plugin 'IOCore v1.0.1' (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
Failed to call hook 'OnEntityKill' on plugin 'IOCore v1.0.1' (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
Failed to call hook 'OnEntityKill' on plugin 'IOCore v1.0.1' (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
Failed to call hook 'OnEntityKill' on plugin 'IOCore v1.0.1' (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
Failed to call hook 'OnEntityKill' on plugin 'IOCore v1.0.1' (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
Failed to call hook 'OnEntityKill' on plugin 'IOCore v1.0.1' (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

Does anyone know how to solve this error?.

IOCore is RustEdit.

Do I update Oxide.Ext.RustEdit.dll or it has nothing to do with it?

It's an error with that extension, which I'd suggest asking about in its site.

Thank you very much Wulf for always being there.

I updated and reinstalled:

Oxide.Ext.RustEdit.dl

Oxide.Ext.RustIO.dll

Oxide (legacy) v2.0.5297

And so the problem was solved.