IOException: 无法从传输连接中读取数据: 连接已关闭。
StackTrace:
   在 System.Net.ConnectStream.IOError(Exception exception, Boolean willThrow)
   在 System.Net.ConnectStream.InternalWrite(Boolean async, Byte[] buffer, Int32 offset, Int32 size, AsyncCallback callback, Object state)
   在 System.Net.ConnectStream.Write(Byte[] buffer, Int32 offset, Int32 size)
   在 DynamicClass.WebDAVClient.ReadCallback(IAsyncResult result)
   在 System.Net.LazyAsyncResult.Complete(IntPtr userToken)
   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.Net.ContextAwareResult.Complete(IntPtr userToken)
   在 System.Net.LazyAsyncResult.ProtectedInvokeCallback(Object result, IntPtr userToken)
   在 System.Net.HttpWebRequest.InvokeGetRequestStreamCallback()
   在 System.Net.HttpWebRequest.EndWriteHeaders_Part2()
   在 System.Net.HttpWebRequest.EndWriteHeaders(Boolean async)
   在 System.Net.HttpWebRequest.WriteHeadersCallback(WebExceptionStatus errorStatus, ConnectStream stream, Boolean async)
   在 System.Net.LazyAsyncResult.Complete(IntPtr userToken)
   在 System.Net.LazyAsyncResult.ProtectedInvokeCallback(Object result, IntPtr userToken)
   在 System.Net.Security._SslStream.StartWriting(Byte[] buffer, Int32 offset, Int32 count, AsyncProtocolRequest asyncRequest)
   在 System.Net.Security._SslStream.WriteCallback(IAsyncResult transportResult)
   在 System.Net.LazyAsyncResult.Complete(IntPtr userToken)
   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.Net.ContextAwareResult.Complete(IntPtr userToken)
   在 System.Net.LazyAsyncResult.ProtectedInvokeCallback(Object result, IntPtr userToken)
   在 System.Net.Sockets.BaseOverlappedAsyncResult.CompletionPortCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* nativeOverlapped)
   在 System.Threading._IOCompletionCallback.PerformIOCompletionCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* pOVERLAP)