SignalR中无法解决“断开连接”方法

Question

我们在SignalR上遇到问题，有时服务器发了以下错误：

2019-01-30 13:20:28,526 [285] [(null)] WARN  HubPipelineModule SignalR Hub Error: System.InvalidOperationException: 'Disconnect' method could not be resolved. No method found with that name.
   at Microsoft.AspNet.SignalR.Hubs.NullMethodDescriptor.<get_Invoker>b__6_0(IHub emptyHub, Object[] emptyParameters)
   at Microsoft.AspNet.SignalR.Hubs.HubDispatcher.Incoming(IHubIncomingInvokerContext context)
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at HubPipelineModule.<>c__DisplayClass1.<<BuildIncoming>b__0>d__3.MoveNext()

断开连接如何突然从集线器中消失？它不是我们创建的方法

SignalR版本：2.4.0