On a multilingual (content negotiated) web site, you want your error documents to be content negotiated as well.
The Apache 2.0 default configuration file contains a configuration section, initially commented out, that allows you to provide error documents in multiple languages customized to the look of your web site, with very little additional work.
Uncomment those lines. You can identify the lines by looking for the following comment in your default configuration file:
# The internationalized error documents require mod_alias, mod_include # and mod_negotiation. To activate them, uncomment the following 30 lines.
In Apache 1.3 this is harder, but there's a solution in the works, as of this writing, that will make it similar to the 2.0 implementation. Check the Apache Cookbook web site for more information.
The custom error documents provided with Apache 2.0 combine a variety of techniques to provide internationalized error messages. As of this writing, these error messages are available in German, English, Spanish, French, Dutch, Swedish, Italian and Portuguese. Based on the language preference set in the client browser, the error message is delivered in the preferred language of the end-user.
Using content negotiation, the correct variant of the document (i.e., the right language) is selected for the user, based on their browser preference settings. For more information about content negotiation, see the content negotiation documentation at http://httpd.apache.org/docs-2.0/content-negotiation.html (for Apache 2.0) or http://httpd.apache.org/docs/content-negotiation.html (for Apache 1.3).
In addition to delivering the error message in the correct language, this functionality also lets you customize the look of these error pages so that they resemble the rest of your web site. To facilitate this, the files top.html and bottom.html, located in the include subdirectory of the error directory, should be modified to look like the standard header and footer content that appears on your web site. The body of the error message documents is placed between the header and the footer to create a page that is less jarring to users when they transition from your main site to the error pages that are generated.
You will also note that the error documents themselves contain SSI directives, which are used to further customize the error documents for the user. For example, in the case of the 404 (file not found) error document, the page will provide a link back to the page that the user came from, if the environment variable HTTP_REFERER is defined, and if that variable is not found, the page will merely notify the user that the URL was not found. Other SSI directives may be put in these documents, if you wish, to further customize them.