.htaccess ErrorDocument 404 Consequences

The ErrorDocument 404 line in the .htaccess file has different consequences depending on whether the destination is specified as URI or URL.

A URL is like: http://example.com/index.html

A URI is a URL minus the domain name part: /index.html

Assuming the site owner wants all 404's to go to the site's index web page and assuming the index web page file name is index.html, these are the two ErrorDocument choices:

ErrorDocument 404 /index.html
ErrorDocument 404 http://example.com/index.html

The first has a URI for a destination. The second a URL.

With the URI version, when a browser asks for a nonexistent page, http://example.com/nonexistent.html for example, the server will send the contents of the index.html web page to the browser. The URL in the browser's address bar will be http://example.com/nonexistent.html

With the URL version, when a browser asks for a nonexistent page, the server will send the browser a 302 redirect to http://example.com/index.html. The browser will redirect to the index.html web page. The URL in the browser's address bar will be http://example.com/index.html

Both versions display the same index web page. The difference is in the URL in the browser's address bar.

Will Bontrager