如何在ASP中返回正确的错误响应。NET MVC 3.0通过JSON?

I'm struggling to resolve this problem. On my local machine (Win7/VS2010/IIS 7.5) and another identical developer's machine, the following code returns the 500 status code, and the response text says "Could not locate user with specified email address".I'm struggling to resolve this problem. On my l