How to fix web api controller unit testing exception - accept header invalid

[ygwild]

I'm using the Request.CreateResponse method in asp.net web api (.net 4.5) to attempt to return a response after a PUT op.\[code\]documentSession.SaveChanges();// Http PUT response must return URI to created / updated resource // Line below throws exception var response = Request.CreateResponse<T>(HttpStatusCode.Created, resource);response.Headers.Location = new Uri(Request.RequestUri, pathToResource);return response;\[/code\]My unit tests currently use this method to setup the request context:\[code\]public static void SetupControllerContext(BaseApiController controller, HttpMethod method){ controller.Request = new HttpRequestMessage(method, "http://localhost"); //controller.Request.Headers.Add("Accept", "application/json"); var configuration = new System.Web.Http.HttpConfiguration(new System.Web.Http.HttpRouteCollection()); controller.Request.Properties["MS_HttpConfiguration"] = configuration;}\[/code\]The exception (thrown on the Request.CreateResponse method above) is:The format of value 'application/json; charset=utf-8' is invalid.Stacktrace:\[code\] at System.Net.Http.Headers.MediaTypeHeaderValue.CheckMediaTypeFormat(String mediaType, String parameterName) at System.Net.Http.Headers.MediaTypeHeaderValue..ctor(String mediaType) at System.Net.Http.ObjectContent.BuildHeaderValue(String mediaType) at System.Net.Http.ObjectContent`1..ctor(T value, MediaTypeFormatter formatter, String mediaType) at System.Net.Http.HttpRequestMessageExtensions.CreateResponse[T](HttpRequestMessage request, HttpStatusCode statusCode, T value, HttpConfiguration configuration) at System.Net.Http.HttpRequestMessageExtensions.CreateResponse[T](HttpRequestMessage request, HttpStatusCode statusCode, T value) at SoftModel.UI.Html.Controllers.BaseApiController.SaveChanges[T](T resource, String pathToResource) in c:\Users\Us\Documents\Visual Studio 2010\Projects\SoftModel\SoftModel.UI.Html\Controllers\BaseApiController.cs:line 113 at SoftModel.UI.Html.Controllers.InstanceController.Put(Record record) in c:\Users\Us\Documents\Visual Studio 2010\Projects\SoftModel\SoftModel.UI.Html\Controllers\InstanceController.cs:line 62 at SoftModel.Tests.InstanceApiControllerTests.Put_Valid_Record_Returns_Record_URI() in c:\Users\Us\Documents\Visual Studio 2010\Projects\SoftModel\SoftModel.Tests\InstanceControllerTests.cs:line 69\[/code\]I've checked the source of the MediaTypeHeaderValue and cannot work out what is wrong?