Error Handling in System.Net.HttpWebRequest::GetResponse()

Question

I have a Powershell script that uses System.Net.HttpWebRequest to communicate with a remote host.

I create the request, set properties accordingly and

Answer 1

Ever tried the try and catch statements? This works fine for me.

ex:

$webclient = new-object system.net.webclient
try {
    $domain = $webclient.downloadstring("http://xrsolis.com") # get a non existent domain
} catch {
    write-host "domain inaccessible"
}

Answer 2

Edit: I misunderstood the question at first, but it turns out that you can retrieve the response header by using the HttpWebResponse.GetResponseHeader() method. If an exception occurs, the HttpWebRequest.GetResponse() method returns $null, and you have to use this code to retrieve the HttpWebResponse object, so that you can call GetResponseHeader() on it:

# If an exception occurs, get the HttpWebResponse object from the WebException object
$HttpWebResponse = $Error[0].Exception.InnerException.Response;

---

I'm pretty sure you'll want to stick with the System.Net.HttpWebRequest instead of the System.Net.WebClient object. Here is an example, similar to what you probably already have:

# Create a HttpWebRequest using the Create() static method
$HttpWebRequest = [System.Net.HttpWebRequest]::Create("http://www.google.com/");

# Get an HttpWebResponse object
$HttpWebResponse = $HttpWebRequest.GetResponse();

# Get the integer value of the HttpStatusCode enumeration
Write-Host -Object $HttpWebResponse.StatusCode.value__;

The GetResponse() method returns a HttpWebResponse object, which has a property named StatusCode, which points to a value in the HttpStatusCode .NET enumeration. Once you get a reference to the enumeration, we use the value__ property to get the integer that is associated with the returned enum value.

If you get a null value from the GetResponse() method, then you'll want to read the most current error message in your catch {..} block. The Exception.ErrorRecord property should be the most helpful.

try {
  $HttpWebResponse = $null;
  $HttpWebRequest = [System.Net.HttpWebRequest]::Create("http://www.asdf.com/asdf");
  $HttpWebResponse = $HttpWebRequest.GetResponse();
  if ($HttpWebResponse) {
    Write-Host -Object $HttpWebResponse.StatusCode.value__;
    Write-Host -Object $HttpWebResponse.GetResponseHeader("X-Detailed-Error");
  }
}
catch {
  $ErrorMessage = $Error[0].Exception.ErrorRecord.Exception.Message;
  $Matched = ($ErrorMessage -match '[0-9]{3}')
  if ($Matched) {
    Write-Host -Object ('HTTP status code was {0} ({1})' -f $HttpStatusCode, $matches.0);
  }
  else {
    Write-Host -Object $ErrorMessage;
  }

  $HttpWebResponse = $Error[0].Exception.InnerException.Response;
  $HttpWebResponse.GetResponseHeader("X-Detailed-Error");
}

http://msdn.microsoft.com/en-us/library/system.net.httpwebrequest.aspx

http://msdn.microsoft.com/en-us/library/system.net.httpstatuscode.aspx

http://msdn.microsoft.com/en-us/library/system.net.httpwebresponse.aspx