c# 抛出异常：System.dll 中的“System.Net.WebException”

Question

I am trying to send a simple HttpWebRequest, where I am trying to logout the current logged in user, The same problem also exists when trying to login the user and I get exception erro "'System.Net.WebException' in System.dll"

So the HttpWebRequest, that I am trying to send is as follows:

HttpWebRequest request = (HttpWebRequest)WebRequest.Create("https://localhost:61000/users/logout");
request.Method = "POST";
try
{
    HttpWebResponse httpResponse = (HttpWebResponse)request.GetResponse();
}
catch (Exception ex)
{
    Debug.WriteLine("Exception Occurred: " ex.Message);
}

I am working with the visual studio 2017 and there I try to look for more information on the below exception: Exception thrown: 'System.Net.WebException' in System.dll

-       $exception  {System.Net.WebException: The SSL connection could not be established, see inner exception. The remote certificate is invalid according to the validation procedure. ---> System.Net.Http.HttpRequestException: The SSL connection could not be established, see inner exception. ---> System.Security.Authentication.AuthenticationException: The remote certificate is invalid according to the validation procedure.
   at System.Net.Security.SslState.StartSendAuthResetSignal(ProtocolToken message, AsyncProtocolRequest asyncRequest, ExceptionDispatchInfo exception)
   at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.ProcessReceivedBlob(Byte[] buffer, Int32 count, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.ProcessReceivedBlob(Byte[] buffer, Int32 count, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.PartialFrameCallback(AsyncProtocolRequest asyncRequest)
--- End of stack trace from previous location where exception was thrown ---
   at System.Net.Security.SslState.ThrowIfExceptional()
   at System.Net.Security.SslState.InternalEndProcessAuthentication(LazyAsyncResult lazyResult)
   at System.Net.Security.SslState.EndProcessAuthentication(IAsyncResult result)
   at System.Net.Security.SslStream.EndAuthenticateAsClient(IAsyncResult asyncResult)
   at System.Net.Security.SslStream.<>c.<AuthenticateAsClientAsync>b__47_1(IAsyncResult iar)
   at System.Threading.Tasks.TaskFactory`1.FromAsyncCoreLogic(IAsyncResult iar, Func`2 endFunction, Action`1 endAction, Task`1 promise, Boolean requiresSynchronization)
--- End of stack trace from previous location where exception was thrown ---
   at System.Net.Http.ConnectHelper.EstablishSslConnectionAsyncCore(Stream stream, SslClientAuthenticationOptions sslOptions, CancellationToken cancellationToken)
   --- End of inner exception stack trace ---
   at System.Net.Http.ConnectHelper.EstablishSslConnectionAsyncCore(Stream stream, SslClientAuthenticationOptions sslOptions, CancellationToken cancellationToken)
   at System.Threading.Tasks.ValueTask`1.get_Result()
   at System.Net.Http.HttpConnectionPool.CreateConnectionAsync(HttpRequestMessage request, CancellationToken cancellationToken)
   at System.Threading.Tasks.ValueTask`1.get_Result()
   at System.Net.Http.HttpConnectionPool.WaitForCreatedConnectionAsync(ValueTask`1 creationTask)
   at System.Threading.Tasks.ValueTask`1.get_Result()
   at System.Net.Http.HttpConnectionPool.SendWithRetryAsync(HttpRequestMessage request, Boolean doRequestAuth, CancellationToken cancellationToken)
   at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
   at System.Net.Http.DiagnosticsHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
   at System.Net.Http.HttpClient.FinishSendAsyncUnbuffered(Task`1 sendTask, HttpRequestMessage request, CancellationTokenSource cts, Boolean disposeCts)
   at System.Net.HttpWebRequest.SendRequest()
   at System.Net.HttpWebRequest.GetResponse()
   --- End of inner exception stack trace ---
   at System.Net.HttpWebRequest.GetResponse()
   at ZenZefi.Program.Main(String[] args) in H:\work\Zenzefi\ZenZefi\ZenZefi\Program.cs:line 25}    System.Net.WebException

Answer 1

Since the exception message is about SSL, i think that the error thrown because invalid or expired SSL certificate.

You can try to ignore them by specifying ValidationCallback before creating a request.

ServicePointManager.ServerCertificateValidationCallback += (sender, cert, chain, sslPolicyErrors) => true;

Thanks to Alex K for reminding me. Accepting invalid, expired or untrusted SSL certificates is really bad workaround. It can absolutely causing serious problem, makes your server become vulnerable. So the best practice here is to ensure that the SSL certificate is valid.

Answer 2

如果您没有创建有效的证书，则会出现安全异常，请在此处找到解决方案如何在 .NET 中验证 HTTPS/SSL 证书的有效性？