Use a Custom 404 Not Found Page on my Project

If you want your project to use a custom page for not found pages instead of the “Maze Found” default one, you can put a 404.html at the top level of your project’s HTML output.

When a 404 is returned, Read the Docs checks if there is a 404.html in the root of your project’s output and uses it if it exists.

As the 404.html will be returned for all the URLs where the real page was not found, all its resources URLs and links must be absolute (starting with a /), otherwise they will not work when a user clicks on them.

In case you don’t want to deal with these links manually, or you want to use the same style as your theme, you can use the sphinx-notfound-page extension.

Using sphinx-notfound-page extension

The sphinx-notfound-page extension automatically creates the proper URLs for your 404 page. Once the extension is installed, it will generate the default 404 page for your project. See its documentation for how to install and custom it.