Reusing WebClient object to send another HTTP request

Question

Can anyone explain me, why I can't reuse WebClient object to send another HTTP POST request?

This code doesn't work:

var client = new WebClient();
client.Headers[HttpRequestHeader.ContentType] = "application/x-www-form-urlencoded";
string buySmsNumberResult = client.UploadString(ApiBuyUrl, apiBuyParams); //it works fine

//but when I try to send another HTTP POST with the existing WebClient object
string updateSmsNumberResult = client.UploadString(ApiUpdateNumberUrl, apiUpdateParams);
//it throws the exception

Exception is:

The remote server returned an error: (400) Bad Request.

But if I recreate WebClient object before the second HTTP POST, it works without any issues.

This code works.

var client = new WebClient();
client.Headers[HttpRequestHeader.ContentType] = "application/x-www-form-urlencoded";
string buySmsNumberResult = client.UploadString(ApiBuyUrl, apiBuyParams); 

//recreating of the WebCLient object
client = new WebClient();
client.Headers[HttpRequestHeader.ContentType] = "application/x-www-form-urlencoded";
string updateSmsNumberResult= client.UploadString(ApiUpdateNumberUrl, apiUpdateParams);

The API, which I'm using there - this is Nexmo API.

Thanks.

Answer 1

Like PHeiberg stated, WebClient clears the Headers after the request is done, so adding them again will make it work.

In answer to LokiSinclair comment about the personal preference to create a new object, I must say that it is not a good practice if you are using an inherited WebClient that uses Cookies and other relevant functionality that you need to share between requests.