HttpResponseException is not handled in a webapi controller in area - asp.net-web-api2

Question

I have two webapi controllers in my MVC 5 project, one in the main domain:
namespace VincConsultancy.Controllers
{
public class QuestionGroupController : ApiController
{
//...
public IEnumerable<SAQQuestionGroup> Get(int id = 0)
{
var groups = (from g in repository.SAQQuestionGroups
where g.RequirementId == id
select g).ToList();
if (groups.Count == 0)
{
string message = string.Format("Groups with Req id = {0} not found", id);
throw new HttpResponseException(
Request.CreateErrorResponse(HttpStatusCode.NotFound, message)
);
}
return groups;
}
}
}
The other one in the area domain:
namespace VincConsultancy.Areas.admin.Controllers
{
public class SAQGroupsController : ApiController
{
//...
public IEnumerable<SAQGroup> Get(int id = 0)
{
var groups = (from g in this.dbCnxt.SAQQustnGroups
where g.RequirementId == id
select g).ToList();
if (groups.Count == 0)
{
string message = string.Format("Groups with Req id = {0} not found", id);
throw new HttpResponseException(
Request.CreateErrorResponse(HttpStatusCode.NotFound, message)
);
}
return groups;
}
}
}
In both controllers, I return error messages by throwing HttpResponseException. Visual Studio pauses the execution at the line of 'throw new HttpResponseException' only in the controller in the admin area, saying an exception occurs but was not handled by user code, that doesnt affect the functionality though, i just need to press the continue button every time. However it doesnt happen to the other controller. So, I am wondering if there is some mechanism handling the exceptions in main domain automatically. The throw-exception line is not supposed to be caught by my code, how should I get rid of visual studio breaking there?