Handling responses

All Execute{Method}Async functions return an instance of RestResponse. Similarly, Execute{Method}Async<T> return a generic instance of RestResponse<T> where T is the response object type.

Response object contains the following properties:

Property	Type	Description
Request	RestRequest	Request instance that was used to get the response.
ContentType	string?	Response content type. Null if response has no content.
ContentLength	long?	Response content length. Null if response has no content.
ContentEncoding	ICollection<string>	Content encoding collection. Empty if response has no content.
Content	string?	Response content as string. Null if response has no content.
IsSuccessfulStatusCode	bool	Indicates if response was successful, so no errors were reported by the server.
ResponseStatus	None, Completed, Error, TimedOut, Aborted	Response completion status. Note that completed responses might still return errors.
IsSuccessful	bool	True when IsSuccessfulStatusCode is true and ResponseStatus is Completed.
StatusDescription	string?	Response status description, if available.
RawBytes	byte[]?	Response content as byte array. Null if response has no content.
ResponseUri	Uri?	URI of the response, which might be different from request URI in case of redirects.
Server	string?	Server header value of the response.
Cookies	CookieCollection?	Collection of cookies received with the response, if any.
Headers	Collection of HeaderParameter	Response headers.
ContentHeaders	Collection of HeaderParameter	Response content headers.
TrailingHeaders	Collection of HeaderParameter	Response trailers (headers sent after the body). Populated on .NET 8+ only, empty otherwise.
ErrorMessage	string?	Transport or another non-HTTP error generated while attempting request.
ErrorException	Exception?	Exception thrown when executing the request, if any.
Version	Version?	HTTP protocol version of the request.
RootElement	string?	Root element of the serialized response content, only works if deserializer supports it.
MergedParameters	ParametersCollection	Combined view of request parameters and client default parameters at execution time.

Merged parameters

The MergedParameters property provides a combined view of the request's own parameters and the client's default parameters as they were at execution time. This is useful for logging or debugging the full set of parameters that were applied to a request, since Request.Parameters only contains the parameters added directly to the request.

var response = await client.ExecuteAsync(request);

foreach (var param in response.MergedParameters) {
    Console.WriteLine($"{param.Name} = {param.Value} ({param.Type})");
}

Trailing headers

Some servers send additional header fields after the response body, known as trailers (see RFC 9110). They are typically used for message integrity checks, signatures, or status information that is only known once the body has been generated. RestSharp exposes them via the TrailingHeaders property, separately from Headers and ContentHeaders:

var response = await client.ExecuteAsync(request);

var digest = response.TrailingHeaders.FirstOrDefault(h => h.Name == "Digest")?.Value;

Trailers are populated on .NET 8 and later, after the response content has been fully read. On .NET Framework and .NET Standard targets, HttpClient does not expose trailers, so the collection is always empty. Trailers are also not available when streaming the response with DownloadStreamAsync, since the body is not read by RestSharp in that case. As with every other response property, TrailingHeaders is only filled in by RestSharp's default response processing: if you supply an AdvancedResponseWriter, your writer receives the raw HttpResponseMessage and must copy its TrailingHeaders itself.

In addition, RestResponse<T> has one additional property:

Property	Type	Description
Data	T?	Deserialized response object. Null if there's no content in the response, deserializer failed to understand the response content, or if request failed.