WebException: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.
--Status: TrustFailure
StackTrace:
   at System.Net.HttpWebRequest.EndGetRequestStream(IAsyncResult asyncResult, TransportContext& context)
   at System.Net.HttpWebRequest.EndGetRequestStream(IAsyncResult asyncResult)
   at DynamicClass.WebDAVClient.ReadCallback(IAsyncResult result)
   at System.Net.LazyAsyncResult.Complete(IntPtr userToken)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Net.ContextAwareResult.Complete(IntPtr userToken)
   at System.Net.LazyAsyncResult.ProtectedInvokeCallback(Object result, IntPtr userToken)
   at System.Net.HttpWebRequest.SetResponse(Exception E)
   at System.Net.ConnectStream.ProcessWriteCallDone(ConnectionReturnResult returnResult)
   at System.Net.ConnectStream.CallDone(ConnectionReturnResult returnResult)
   at System.Net.ConnectStream.IOError(Exception exception, Boolean willThrow)
   at System.Net.ConnectStream.WriteHeadersCallback(IAsyncResult ar)
   at System.Net.LazyAsyncResult.Complete(IntPtr userToken)
   at System.Net.LazyAsyncResult.ProtectedInvokeCallback(Object result, IntPtr userToken)
   at System.Net.TlsStream.ResumeIOWorker(Object result)
   at System.Net.TlsStream.WakeupPendingIO(IAsyncResult ar)
   at System.Net.LazyAsyncResult.Complete(IntPtr userToken)
   at System.Net.LazyAsyncResult.ProtectedInvokeCallback(Object result, IntPtr userToken)
   at System.Net.Security.SslState.FinishHandshake(Exception e, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.WriteCallback(IAsyncResult transportResult)
   at System.Net.LazyAsyncResult.Complete(IntPtr userToken)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Net.ContextAwareResult.Complete(IntPtr userToken)
   at System.Net.LazyAsyncResult.ProtectedInvokeCallback(Object result, IntPtr userToken)
   at System.Net.Sockets.BaseOverlappedAsyncResult.CompletionPortCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* nativeOverlapped)
   at System.Threading._IOCompletionCallback.PerformIOCompletionCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* pOVERLAP)

AuthenticationException: The remote certificate is invalid according to the validation procedure.
StackTrace:
   at System.Net.TlsStream.EndWrite(IAsyncResult asyncResult)
   at System.Net.ConnectStream.WriteHeadersCallback(IAsyncResult ar)