What is the proper way to catch and identify the HttpRequestException “The remote name could not be resolved: 'www.example.com'”?

I want to be able to catch and identify the exceptions that belong to this specific type and then return a suitable error message. What is the proper way to do that in a catch block?

2 Answers
2

The exception you need to catch is an HttpRequestException specifically with an InnerException that is a WebException and has a Status property with a value of WebExceptionStatus.NameResolutionFailure.

HttpRequestException

InnerException

WebException

Status

WebExceptionStatus.NameResolutionFailure

Fortunately, using C# 6.0 exception filters, it's now easy to catch only an exception that fulfills these specific criteria:

var hc=new HttpClient();
try
{
(await hc.GetStringAsync("https://www.googggle.com"));

}
catch(HttpRequestException ex)
when ((ex.InnerException as WebException)?.Status ==
WebExceptionStatus.NameResolutionFailure)
{
//yay. localization-proof
Console.WriteLine("dns failed");
}


First, catch HttpRequestException in catch block

catch (HttpRequestException ex){}


Then if you need to closely identify the message, use ex.Message

if (ex.Message.StartsWith("The remote name could not be resolved:"))
{
//do the rest
{


What about using the HResult instead of the exception message?
– Nimish David Mathew
Jun 29 at 9:57

Fails in any non-English locale.
– spender
Jun 29 at 10:00

Not sure. Last time I wanted to use HResult it was giving me same HResult code for different exceptions, but I don't remember it well so you should try it
– tomassino
Jun 29 at 10:01

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