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 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 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"><web-app ...>
    <error-page>
        <location>/general-error.html</location>
    </error-page>
</web-app></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"><error-page>
    <!-- Missing login -->
    <error-code>401</error-code>
    <location>/general-error.html</location>
</error-page>
<error-page>
    <!-- Forbidden directory listing -->
    <error-code>403</error-code>
    <location>/general-error.html</location>
</error-page>
<error-page>
    <!-- Missing resource -->
    <error-code>404</error-code>
    <location>/Error404.html</location>
</error-page>
<error-page>
    <!-- Uncaught exception -->
    <error-code>500</error-code>
    <location>/general-error.html</location>
</error-page>
<error-page>
    <!-- Unsupported servlet method -->
    <error-code>503</error-code>
    <location>/general-error.html</location>
</error-page></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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