HttpWebRequest: Remote server returns error 503 Server Unavailable

 

I have a client server application written in C# .Net 2.0. I have had the client/server response/request code running for 4 years(!). Recently, on a specific machine, the client can not connect to server:

on the code line:

HttpWebResponse response = (HttpWebResponse)request.GetResponse();

WebException: The remote server returned an error: (503) Server Unavailable.
Message="The remote server returned an error: (503) Server Unavailable."
Status System.Net.WebExceptionStatus.ProtocolError

I believe this issue is machine-specific since i never had this issue on any other machine.

Is there something I need to configure on that machine? What did I miss?

HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(string.Format("http://{0}:{1}/", server, httpPort));

request.ContentType = "application/x-www-form-urlencoded";

string msgStr = msgString;

byte[] buffer = Encoding.UTF8.GetBytes(msgStr);

request.ContentLength = buffer.Length;

request.Method = "POST";

 

try {

System.IO.Stream requestStream = request.GetRequestStream();

requestStream.Write(buffer, 0, buffer.Length);

requestStream.Close();

requestStream.Dispose();

 

HttpWebResponse response = (HttpWebResponse)request.GetResponse();

 

byte[] inBuffer = new byte[10000];

Stream responseStream = response.GetResponseStream();

int iBytes = responseStream.Read(inBuffer, 0, inBuffer.Length);

 

StringBuilder sb = new StringBuilder(10000);

 

while (iBytes > 0) {

sb.Append(Encoding.UTF8.GetString(inBuffer, 0, iBytes));

iBytes = responseStream.Read(inBuffer, 0, inBuffer.Length);

}

 

response.Close();

responseStream.Close();

responseStream.Dispose();

 

if (!string.IsNullOrEmpty(sb.ToString())) {

message = HandleMessage(sb.ToString());

} else { //bug 58

message = HandleEmptyMessage(msgString);

}

} catch (System.Net.WebException we) {

_connected = false;

EventsHelper.AsyncFire(ConnectionLost, this, EventArgs.Empty);

throw new Exception(we.Message);

}

 

[Answers 1]

If it is only one machine it is probably environmental. It could be a DNS issue, a firewall issue, a router issue, an ISP issue

 

[Answers 2]

Thanks Jared! it was indeed a wrong network configuration.

 

 

From: https://stackoverflow.com/questions/14504165/remote-server-returns-error-503-server-unavailable