Data bound request does not support "application/json" content type. 

The exception listed in the log: 

[Telerik.TestStudio.Load.Agent.exe(3640:5),Load] AsyncTaskMethodBuilder`1.Start() : An outstanding request finished, but was marked as a failed request.
[Telerik.TestStudio.Load.Agent.exe(3640:3),Error] OutstandingRequest.Run() : EXCEPTION! (see below)
     Situation: Exception during HTTP Request, url [https://server.com]
     Outer Exception Type: System.NotImplementedException
     Message: Content type "application/json" is not implemented.
     HRESULT: 0x80004001 (Official ID (if app.) = E_NOTIMPL, Error Bit = FAILED, Facility = FACILITY_NULL, Code = 16385)
     Call Stack:
          at Telerik.TestingFramework.Net.HttpUtilities.SerializeContent(String strContentEncoding, ContentType contentType, Object objTransformedContent)
          at Telerik.TestStudio.Load.Http.OutstandingRequest.ApplyBindingsToRequest(HttpRequestBuilder requestBuilder)
          at Telerik.TestStudio.Load.Http.OutstandingRequest.<Run>d__24.MoveNext()