Fix a 500 "Internal Server Error"

This guide is for you if you encounter a 500 error that may have various causes generally related to the development of your site on a Web Hosting, particularly with the rewrites in your .htaccess files.

Preamble

• Apache2, in place on the servers, no longer supports certain modules such as mod_auth_anon, mod_auth_dbm, mod_authz_dbm, mod_cern_meta, mod_imap, mod_imagemap, mod_mime_magic
• Apache2 is strict about syntax errors and when it encounters syntax errors in a .htaccess file, this can result in 500 Internal Server Error errors or unexpected URL rewrite errors
   

Examples of syntaxes and correction

In this first example, the syntax error is that the rewrite rule does not specify the HTTP redirection response code to return.

RewriteRule ^articles/([0-9]+)/$ /article.php?id=$1 [L]

The correction adds the directive R=301 to specify that the redirection should return a 301 (permanent) code:

RewriteRule ^articles/([0-9]+)/$ /article.php?id=$1 [L,R=301]

In this second example, the syntax error is that the Options directive does not correctly specify the options to enable or disable.

Options -Indexes FollowSymLinks

The correction adds the sign "+" to specify that FollowSymLinks should be enabled rather than disabled:

Options -Indexes +FollowSymLinks

Fix these errors

• If the first page or another page displays a 500 error, rename the .htaccess file or comment out all lines with # and uncomment line by line until you find the problematic section.
• If the error occurs after a modification made to one of your pages, the simplest solution is to restore the previous version of the file.