Picto thématique

Rule n° 215 - The server sends a 404 HTTP error code for resources not found

This is not only to inform your visitor to an address error: it is also useful for various tools such as search engines. The call of an error in address should always result in a 404 (not found) by the server. Curiously, in some cases, the server or CMS used return a 404 error page accompanied by a code 200 (which means "OK, everything is fine").

#Eco-conception #SEO #Server and performance #Development


  • Enable the automated detection of incorrect URLs.
  • Send reliable information to the browser.
  • Reduce the energy impact related to the consultation of the site.
  • Improve the way content is taken into account by search engines and indexing tools.


Modify the web server configuration to send the user to a customised page when the requested resource does not exist

If the main server configuration is not directly accessible and if the environment allows it, use a local configuration by directory. For example, the Apache environment authorises the creation of an .htaccess file containing directives relating to error handling: ErrorDocument 404 /mapage.html.


For each site checked:

  • Enter the URL address of the site followed by random characters (such as http://www.example.com/lsghlshdgkjsdgk).
  • Check with a development tool that the status shown is 404 not found.

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