ASP.NET Web API: Non-descriptive 500 Internal Server Error

Question

As title says, I’ve got 500 Internal Server Error from GET request to an IQueryable action. The body of the error is empty. That error happens after my action returns result

Answer 1

This may be related to circular reference.

http://www.asp.net/web-api/overview/formats-and-model-binding/json-and-xml-serialization#handling_circular_object_references

Try adding the following code to Application_Start method in the Global.asax file:

 var json = GlobalConfiguration.Configuration.Formatters.JsonFormatter;
 json.SerializerSettings.PreserveReferencesHandling = Newtonsoft.Json.PreserveReferencesHandling.All;