Error when sending large data with HTTP Post

Question

I am using the following code to send data to an web API from a WinForms app:

private string SendBatch(string URL, string POSTdata)
{
    string responseData = "";
    try
    {
        HttpWebRequest hwrequest = (HttpWebRequest)WebRequest.Create(URL);
        hwrequest.Timeout = 600000;
        hwrequest.KeepAlive = true;
        hwrequest.Method = "POST";
        hwrequest.ContentType = "application/x-www-form-urlencoded";

        byte[] postByteArray = System.Text.Encoding.UTF8.GetBytes("data=" + POSTdata);

        hwrequest.ContentLength = postByteArray.Length;

        System.IO.Stream postStream = hwrequest.GetRequestStream();
        postStream.Write(postByteArray, 0, postByteArray.Length);
        postStream.Close();

        HttpWebResponse hwresponse = (HttpWebResponse)hwrequest.GetResponse();
        if (hwresponse.StatusCode == System.Net.HttpStatusCode.OK)
        {
            System.IO.StreamReader responseStream = new System.IO.StreamReader(hwresponse.GetResponseStream());
            responseData = responseStream.ReadToEnd();
        }
        hwresponse.Close();
    }
    catch (Exception e)
    {
        responseData = "An error occurred: " + e.Message;
    }
    return responseData;

    }
}

When I send a small amount of data, the API receives the data without any issues. However, when I try to send a large amount of data (30MB+) I get an error from the API that I have sent through malformed data.

I have set the timeout to 10 minutes and I receive the error after around 2 minutes.

According to the questions I have gone through on SO, there isn't a limit to the post size and there is no limit on the API.

I've been trying for a few days to find a solution so any pointers will be GREATLY appreciated.

Thanks!

score 2 · Answer 1 · edited May 23 '17 at 12:14

2

There is a maximum default size to the http post default is set to 4Mg in IIS. You have to change this to allow larger streams.

http://support.microsoft.com/default.aspx?scid=kb;EN-US;295626

Here is an example of how to increase this limit.

IIS 7 httpruntime maxRequestLength limit of 2097151

edited May 23 '17 at 12:14

Community

1
1

answered Oct 09 '13 at 03:22

Marko

2,734
24
24

I'm not running this code from a website, it's from a winforms app. Sorry, I should have mentioned that. I know that I can send 20MB with no issues so the limit is probably somewhere between 20MB and 30MB. – Daniel Gee Oct 09 '13 at 03:38
Are you posting from a Win forms app to a website? – Chris McKelt Oct 09 '13 at 03:54
Yes, I am. I've updated the question. (Sorry, I forgot to add it when I asked.) – Daniel Gee Oct 09 '13 at 04:03
Ok - do you have access to the site? Is it .Net can you change the web.config? Is it IIS? – Chris McKelt Oct 09 '13 at 04:07
I don't have access to the site but the API coders say that they have many people uploading much bigger files. – Daniel Gee Oct 09 '13 at 05:44

score 1 · Answer 2 · answered Oct 09 '13 at 04:14

If you own the site checkout IIS Request limits

http://www.iis.net/configreference/system.webserver/security/requestfiltering/requestlimits

<system.webServer>
    <security>
      <requestFiltering>
        <requestLimits maxAllowedContentLength="4294967295" />

score 0 · Answer 3 · answered Oct 09 '13 at 04:32

0

Try setting the HttpWebRequest.SendChunked Property to true.

answered Oct 09 '13 at 04:32

Dijkgraaf

11,049
17
42
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I gave this a try. It didn't help :( – Daniel Gee Oct 09 '13 at 05:44

Error when sending large data with HTTP Post

3 Answers3