404 Not Found pages
If you want your project to use a custom or branded 404 Not Found page,
you can put a 404.html or 404/index.html at the top level of your project’s HTML output.
How it works
When our servers return a 404 Not Found error,
we check if there is a 404.html or 404/index.html in the root of your project’s output.
The following locations are checked, in order:
/404.htmlor404/index.htmlin the current documentation version./404.htmlor404/index.htmlin the default documentation version.
Tool integration
Documentation tools will have different ways of generating a 404.html or 404/index.html file.
We have examples for some of the most popular tools below.
We recommend the sphinx-notfound-page extension,
which Read the Docs maintains.
It automatically creates a 404.html page for your documentation,
matching the theme of your project.
See its documentation for how to install and customize it.
If you want to create a custom 404.html,
Sphinx uses html_extra_path option to add static files to the output.
You need to create a 404.html file and put it under the path defined in html_extra_path.
If you are using the DirHTML builder,
no further steps are required.
Sphinx will automatically apply the <page-name>/index.html folder structure to your 404 page:
404/index.html.
Read the Docs also detects 404 pages named this way.
MkDocs automatically generates a 404.html which Read the Docs will use.
However, assets will not be loaded correctly unless you define the site_url configuration value as your site’s
canonical base URL.