Url rewrite by global asax and error 404 in asp net


ASP.NET is a popular language used for building web applications. One challenge developers face is handling URL rewriting and managing 404 pages. In this article, we will explore how to solve this using ASP.NET and provide examples to illustrate the solutions.

URL Rewriting

URL rewriting is the process of modifying the URL of a web page to make it more user- or search engine optimized. In ASP.NET, we can achieve URL rewriting by using the Global.asax file.

To start, let's create a new ASP.NET project and open the Global.asax file. In the Application_Start event, we can define our URL rewriting rules using the RouteTable class. Here's an example:

 void Application_Start(object sender, EventArgs e)
    RouteTable..MapPageRoute("ProductDetails", "products/{id}", "~/ProductDetails.aspx");

In the above example, we define a route named “ProductDetails” that maps the URL pattern “products/{id}” to the “ProductDetails.aspx” page. The {id} placeholder can be used to capture the product ID from the URL.

Error 404 Handling

When a user requests a page that does not exist, the server returns a 404 error. In ASP.NET, we can customize the error handling for 404 errors by using the web.config file.

To 404 errors, we need to add the following to the web.config file:


In the above configuration, we set the mode to “On” and specify the defaultRedirect page for all errors. We also define a specific error handling for the 404 status code, redirecting to the “~/ErrorPages/404.aspx” page.


Handling URL rewriting and error 404 pages in ASP.NET is essential for creating user-friendly and search engine optimized web applications. By using the Global.asax file for URL rewriting and the web.config file for error handling, developers can easily solve these challenges. The examples provided in this article demonstrate the implementation of these solutions in ASP.NET.

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