AggregateException: 发生一个或多个错误。
--InnerExceptions: System.Collections.ObjectModel.ReadOnlyCollection`1[System.Exception]
StackTrace:
   在 System.Threading.CancellationTokenSource.ExecuteCallbackHandlers(Boolean throwOnFirstException)
   在 System.Threading.CancellationTokenSource.NotifyCancellation(Boolean throwOnFirstException)
   在 System.Threading.CancellationTokenSource.TimerCallbackLogic(Object obj)
   在 System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   在 System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   在 System.Threading.TimerQueueTimer.CallCallback()
   在 System.Threading.TimerQueueTimer.Fire()
   在 System.Threading.TimerQueue.FireNextTimers()

NullReferenceException: 未将对象引用设置到对象的实例。
StackTrace:
   在 MySqlConnector.Core.ServerSession.<>c__DisplayClass99_0.<OpenTcpSocketAsync>b__0()
   在 System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   在 System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   在 System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   在 System.Threading.CancellationCallbackInfo.ExecuteCallback()
   在 System.Threading.CancellationTokenSource.ExecuteCallbackHandlers(Boolean throwOnFirstException)