Error handling

If there is a network transport error (network is down, failed DNS lookup, etc), or any kind of server error (except 404), RestResponse.ResponseStatus will be set to ResponseStatus.Error, otherwise it will be ResponseStatus.Completed.

If an API returns a 404, ResponseStatus will still be Completed. If you need access to the HTTP status code returned you will find it at RestResponse.StatusCode. The Status property is an indicator of completion independent of the API error handling.

Normally, RestSharp doesn't throw an exception if the request fails.

However, it is possible to configure RestSharp to throw in different situations, when it normally doesn't throw in favour of giving you the error as a property.

FailOnDeserializationErrorChanges the default behavior when failed deserialization results in a successful response with an empty Data property of the response. Setting this property to true will tell RestSharp to consider failed deserialization as an error and set the ResponseStatus to Error accordingly.
ThrowOnDeserializationErrorChanges the default behavior when failed deserialization results in empty Data property of the response. Setting this property to true will tell RestSharp to throw when deserialization fails.
ThrowOnAnyErrorSetting this property to true changes the default behavior and forces RestSharp to throw if any errors occurs when making a request or during deserialization.

Those properties are available for the RestClient instance and will be used for all request made with that instance.


Please be aware that deserialization failures will only work if the serializer throws an exception when deserializing the response. Many serializers don't throw by default, and just return a null result. RestSharp is unable to figure out why null is returned, so it won't fail in this case. Check the serializer documentation to find out if it can be configured to throw on deserialization error.

There are also slight differences on how different overloads handle exceptions.

Asynchronous generic methods GetAsync<T>, PostAsync<T> and so on, which aren't a part of RestClient interface (those methods are extension methods) return Task<T>. It means that there's no RestResponse to set the response status to error. We decided to throw an exception when such a request fails. It is a trade-off between the API consistency and usability of the library. Usually, you only need the content of RestResponse instance to diagnose issues and most of the time the exception would tell you what's wrong.

Below you can find how different extensions deal with errors. Note that functions, which don't throw by default, will throw exceptions when ThrowOnAnyError is set to true.

FunctionThrows on errors

In addition, all the functions for JSON requests, like GetJsonAsync and PostJsonAsyn throw an exception if the HTTP call fails.