<p>Allows you te set a page to be used as the 404 page. In order for the plugin to work you need to make some modifications to the <code>404.php</code> file in your theme. I set it this way so that the 404 page could be formatted to fit the theme, or can be set more dynamically.</p>
<p>For more information and sample code: http://www.reitzdesigns.com/2010/08/dynamic-404-page-wordpress-plugin/</p>
<p>Although this plugin will work with WordPress 2.8, it’s better suited for version 3.x.</p>


Dynamic 404 Page

Allows you to select a page to use as the content of your 404 page.

Jon Christopher

Peter Raschendorfer

NerdPress

<p>Bringing visitors to your website takes time and effort. Every visitor is important. The default 404 error page of most themes does not provide any information on what to find on your site. A first-time visitor, who does not know you, is left in a dead end and leaves your website. Set up a helpful custom 404 error page to keep them on your site!</p>
<p>This handy plugin allows you to easily create your own 404 error page without any effort and it works with almost every theme.</p>
<h3>Out of Retirement!</h3>
<p>NerdPress has adopted Smart Custom 404 Page! <a href="https://www.nerdpress.net/announcing-404-page/" rel="nofollow ugc">Read the announcement here.</a></p>
<p>We’ve been fans of this plugin for many years, and we’re grateful for Peter’s many years of service to the community. Peter retired from plugin development in October 2023, so we’ve jumped in to help ensure this plugin continues to work well now and in the future.</p>
<h3>Usage</h3>
<p>Create your custom 404 error page just like any other page using the WordPress Editor (<code>Pages > Add New</code>). Then go to <code>Appearance > 404 Error Page</code> and select the created page as your custom 404 error page. That’s it!</p>
<h3>Why use this plugin?</h3>
<p>Unlike similar plugins the 404page plugin <strong>does not create redirects</strong>. That’s <strong>quite important</strong> because a correct code 404 is delivered which tells search engines that the page does not exist and has to be removed from the index.</p>
<p>Additionally, the 404page plugin <strong>does not create additional server requests</strong>.</p>
<h3>Requirements</h3>
<p>The only requirement for this plugin is that you change the Permalink Structure in <code>Settings > Permalinks</code> to anything else but “Plain.” This also activates the WordPress 404 error handling.</p>
<h3>Block & Shortcode</h3>
<h4>Block</h4>
<p>The Plugin offers a block “URL causing 404 error” for the block-based editor to show the URL that caused the error. The block offers three display options:</p>
<ul>
<li>“Page” to show the page including path ( e.g. <code>does/not/exist</code> )</li>
<li>“Domain Path” to show the URL without protocol and parameters ( e.g. <code>example.com/does/not/exist</code> )</li>
<li>“Full” to show the complete URL ( e.g. <code>https://example.com/does/not/exist?p=1</code> )</li>
</ul>
<h4>Shortcode</h4>
<p>The Plugin offers a shortcode “pp_404_url” for the classic editor to show the URL that caused the error. There are three possible options:</p>
<ul>
<li><strong><code>[pp_404_url page]</code></strong> to show the page including path ( e.g. <code>does/not/exist</code> )</li>
<li><strong><code>[pp_404_url domainpath]</code></strong> to show the URL without protocol and parameters ( e.g. <code>example.com/does/not/exist</code> )</li>
<li><strong><code>[pp_404_url]</code></strong> or <strong><code>[pp_404_url full]</code></strong> to show the complete URL ( e.g. <code>https://example.com/does/not/exist?p=1</code> )</li>
</ul>
<h3>Plugin Privacy Information</h3>
<ul>
<li>This plugin does not set cookies</li>
<li>This plugin does not collect or store any data</li>
<li>This plugin does not send any data to external servers</li>
</ul>
<h3>For developers</h3>
<h4>Action Hook</h4>
<p>The plugin adds an action hook <code>404page_after_404</code> which you can use to add extra functionality. The exact position the action occurs after an 404 error is detected depends on the Operating Method. Your function must not generate any output. There are no parameters.</p>
<h4>Constant</h4>
<p>If the 404page plugin is installed and activated it defines the PHP constant <code>PP_404</code>. Check existence of it to detect the 404page plugin.</p>
<h4>Functions</h4>
<p>The Plugin provides the following functions:</p>
<ul>
<li><strong><code>pp_404_is_active()</code></strong> to check if there is a custom 404 page selected and the selected page exists</li>
<li><strong><code>pp_404_get_page_id()</code></strong> to get the ID of the 404 page </li>
<li><strong><code>pp_404_get_all_page_ids()</code></strong> to get an array of page IDs in all languages</li>
<li><strong><code>pp_404_get_the_url( $type )</code></strong> to get the URL that caused the 404 error
<ul>
<li>Parameter $type string Optional</li>
<li>“page” to get the page including path ( e.g. <code>does/not/exist</code> )</li>
<li>“domainpath” to get the URL without protocol and parameters ( e.g. <code>example.com/does/not/exist</code> )</li>
<li>“full” (default) to get the complete URL ( e.g. <code>https://example.com/does/not/exist?p=1</code> )</li>
</ul>
</li>
</ul>
<h4>Native Mode</h4>
<p>If you are a theme developer you can add native support for the 404page plugin to your theme for full control.</p>


Smart Custom 404 Error Page


Many thanks to @nerdpressteam for adopting my plugin and continuing the work


Thank you

Create a custom 404 error page the easy way! No coding, and no redirects.

Dynamic 404 Page vs Smart Custom 404 Error Page