How to Implement Custom Error Handling in ASP.NET MVC using Application_Error?

Use the Application_Error event of Global.asax to implement custom error handling in ASP.NET MVC

The Application_Error event in the Global.asax file in ASP.NET MVC allows developers to handle unhandled exceptions and errors in the application. A common practice is to redirect users to a specific error page based on the error HTTP status code.

To do this, you can modify the Application_Error event handler as follows:

<code class="language-csharp">protected void Application_Error(object sender, EventArgs e)
{
    Exception exception = Server.GetLastError();
    Response.Clear();

    HttpException httpException = exception as HttpException;
    if (httpException != null)
    {
        string action;

        switch (httpException.GetHttpCode())
        {
            case 404:
                // 页面未找到
                action = "HttpError404";
                break;
            case 500:
                // 服务器错误
                action = "HttpError500";
                break;
            default:
                action = "General";
                break;
        }

        // 清除服务器上的错误
        Server.ClearError();

        Response.Redirect(String.Format("~/Error/{0}/?message={1}", action, exception.Message));
    }
}</code>

In this improved code, we redirect directly to the controller/action and pass the error details as query string parameters instead of creating a new route for the error controller. The Error controller will then receive the message and display it using the view specified in the action method.

<code class="language-csharp">// GET: /Error/HttpError404
public ActionResult HttpError404(string message)
{
    return View("SomeErrorView", message);
}</code>

This approach simplifies error handling and avoids the need for additional routing. However, there are trade-offs to be aware of, for example, performance issues may arise if there are a large number of loops or session creations during error handling.

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