WebException: 请求被中止: 未能创建 SSL/TLS 安全通道。
--Status: SecureChannelFailure
StackTrace:
   在 System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
   在 DynamicClass.WebDAVClient.FinishUpload(IAsyncResult result)
   在 System.Net.LazyAsyncResult.Complete(IntPtr userToken)
   在 System.Net.ContextAwareResult.CaptureOrComplete(ExecutionContext& cachedContext, Boolean returnContext)
   在 System.Net.ContextAwareResult.FinishPostingAsyncOp()
   在 System.Net.HttpWebRequest.BeginGetResponse(AsyncCallback callback, Object state)
   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)