Most WordPress themes will have a 404 error page built in, as there is default template structure built into WordPress for displaying a 404 page (Not Found). WordPress will automatically display the built-in 404 page if the Not Found error occurs.
If your theme doesn’t have one or if you are looking to further customise your default WordPress 404 error page, this short guide might be of help.
A custom 404 page needs to provide helpful information to your visitors that have reached a non-existent page on your site. You should clearly mention that the page doesn’t exist on the website and provide additional information such as a search box that can help users to find what they are looking for on your website.
An effective 404 page will help you retain visitors and encourage them to further explore your website. You might consider displaying a helpful message to inform the visitors that the page wasn’t found on your website and encourage users to report the broken link that led to the error page. A site map with links to the homepage or latest blog posts can be very helpful to your lost users.
Be sure to keep the design and branding of the 404 page consistent with other pages on your website. Having an effective 404 error page is really useful for your visitors and can be important from an SEO perspective. You should be tracking your 404 errors and creating redirects to the appropriate pages.
Smart Custom 404 Error Page Plugin is one of the best plugins that is helpful to create the 404 error pages the right way. The plugin does not create additional server requests as it doesn't create any other redirects. The plugin makes it easy to create custom 404 page just like any other page on WordPress.
Simply create a 'New Page' on your website or blog and publish it. Then go to ‘Appearance’ -> ‘404 Error Page’ and select the page that you just published for your custom 404 error page. You can click on the Test 404 Error button to check if it works as intended. Click save changes if you are happy with how your 404 page looks.
Another plugin that lets you control your custom 404 page, is the Custom 404 Pro Plugin. This plugin lets you assign any pages that you have created as custom 404 pages for your WordPress website. It will replace your default 404 page if you already have one included in your theme.
This plugin also allows you to specify a URL for a page or post that should be redirected to in the case of a 404 error. The plugin also has a 404 Logs section, that will show you details such as what keywords lead the visitors to the 404 error URL on your site.
You can define the settings and make the changes in the admin page of the plugin.