I am getting the following error which may have been introduced with today's mandatory patch

MissingFieldException: Field not found: ulong .BasePlayer.userID Due to: Could not find field in class
  at ConsoleSystem.Internal (ConsoleSystem+Arg arg) [0x0005b] in <001af2b23ca5408d923605de238c60ed>:0 
UnityEngine.DebugLogHandler:Internal_LogException(Exception, Object)
UnityEngine.DebugLogHandler:LogException(Exception, Object)
UnityEngine.Logger:LogException(Exception, Object)
UnityEngine.Debug:LogException(Exception)
ConsoleSystem:Internal(Arg)
ConsoleSystem:Run(Option, String, Object[])
ConsoleNetwork:OnClientCommand(Message)
ServerMgr:OnNetworkMessage(Message)
Facepunch.Network.Raknet.Server:ProcessRead(NetRead)
Network.BaseNetwork:Cycle()
MonoMod.Utils.DynamicMethodDefinition:ServerMgr.Update_Patch0(ServerMgr)