Apache mod_rewrite Errors — URL Rewriting, .htaccess, and Redirect Loop Issues

Fix Apache mod_rewrite errors including .htaccess not working, redirect loops, RewriteRule syntax errors, and clean URL routing failures. This guide covers everything you need to know about this topic, including common causes, step-by-step solutions, and answers to frequently asked questions.

Here are the key things to understand: mod_rewrite transforms URLs using regular expressions and rewrite rules. .htaccess files allow per-directory configuration but must be enabled with AllowOverride All. Redirect loops occur when a RewriteRule matches its own output, creating infinite redirects. RewriteCond (conditions) and RewriteRule (actions) work together for URL transformation. The [L] flag stops processing further rules; [R=301] sends a permanent redirect. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: AllowOverride set to None in Apache config — .htaccess rules are ignored. mod_rewrite module not enabled: 'a2enmod rewrite' not run. RewriteRule matching its own rewritten URL causing a redirect loop. Incorrect regex in RewriteRule not matching the intended URL pattern. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Enable mod_rewrite: 'sudo a2enmod rewrite && sudo systemctl restart apache2'. Enable .htaccess: set 'AllowOverride All' in the <Directory> block of your VirtualHost config. Test rewrite rules: enable RewriteLog (Apache 2.2) or 'LogLevel alert rewrite:trace3' (Apache 2.4) for debugging. Fix redirect loops: add 'RewriteCond %{ENV:REDIRECT_STATUS} 200 [OR] RewriteCond %{REQUEST_URI} ^/target [R=0]' to stop re-processing. Verify syntax: 'apachectl configtest' or 'apache2ctl -t' to check for configuration errors. If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

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