How to Define a Default Error Page for Unspecified Errors in Web Applications?

Customizing Error Handling in Web Applications

When users encounter errors on a web application, it's essential to provide informative and helpful error pages. The <error-page> element in web.xml allows developers to specify custom error pages for specific error codes.

Default Error Page for Unspecified Errors

To provide a default error page for errors not covered by explicit <error-page> elements, follow these steps:

Step 1: Using Servlet 3.0 or Newer

For Servlet 3.0 or newer, you can simply specify the default error page as follows:

<code class="xml">&lt;web-app ...&gt;
    &lt;error-page&gt;
        &lt;location&gt;/general-error.html&lt;/location&gt;
    &lt;/error-page&gt;
&lt;/web-app&gt;</code>

Step 2: Using Servlet 2.5

For Servlet 2.5 and earlier versions, there is no built-in option to specify a default error page. However, you can work around this limitation by explicitly defining error pages for common HTTP errors:

<code class="xml">&lt;error-page&gt;
    &lt;!-- Missing login --&gt;
    &lt;error-code&gt;401&lt;/error-code&gt;
    &lt;location&gt;/general-error.html&lt;/location&gt;
&lt;/error-page&gt;
&lt;error-page&gt;
    &lt;!-- Forbidden directory listing --&gt;
    &lt;error-code&gt;403&lt;/error-code&gt;
    &lt;location&gt;/general-error.html&lt;/location&gt;
&lt;/error-page&gt;
&lt;error-page&gt;
    &lt;!-- Missing resource --&gt;
    &lt;error-code&gt;404&lt;/error-code&gt;
    &lt;location&gt;/Error404.html&lt;/location&gt;
&lt;/error-page&gt;
&lt;error-page&gt;
    &lt;!-- Uncaught exception --&gt;
    &lt;error-code&gt;500&lt;/error-code&gt;
    &lt;location&gt;/general-error.html&lt;/location&gt;
&lt;/error-page&gt;
&lt;error-page&gt;
    &lt;!-- Unsupported servlet method --&gt;
    &lt;error-code&gt;503&lt;/error-code&gt;
    &lt;location&gt;/general-error.html&lt;/location&gt;
&lt;/error-page&gt;</code>

This specifies error pages for the most common HTTP errors, but you may need to adjust the list based on the specific errors your application may encounter.

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