How To Debug A Non-Working .htaccess RewriteRule?

Testing .htaccess Functionality

To check if Apache is reading your .htaccess file, you can add invalid syntax to the file. This method helps you confirm that Apache is processing the file.

Add a random string of characters, like "foo bar" or "abcdefg", into your .htaccess file. Put this text near the top of the file, after the "RewriteEngine On" directive if it's present.

After adding the invalid syntax, try to access your website. If Apache is reading the .htaccess file, you should see a 500 Internal Server Error. This error shows that Apache found an issue while processing the file, confirming that it's being read.

If you don't see a 500 error, it might mean that Apache is not reading your .htaccess file. In this case, you'll need to check your Apache configuration to make sure it's set up to use .htaccess files.

Remember to remove the invalid syntax after testing to restore your website's normal function.

<Directory /path/to/your/website>
    AllowOverride All
</Directory>

Configuring Apache to Read .htaccess

To make Apache use your .htaccess file, you need to set it up correctly. Follow these steps:

1. Find the Apache configuration file: The main Apache configuration file is usually named httpd.conf or apache2.conf. On most Linux systems, it's in /etc/apache2/ or /etc/httpd/. On Windows, it's often in the Apache installation directory.

2. Enable the rewrite module: Look for this line in the configuration file:

   LoadModule rewrite_module modules/mod_rewrite.so

   If the line starts with #, remove the # to enable the module.

3. Set AllowOverride directive: Find the section for your website's root directory. In this section, set the AllowOverride directive to All:

   <Directory /path/to/your/website>
      AllowOverride All
   </Directory>

   This allows .htaccess files to override server configurations.

After making these changes, save the configuration file and restart Apache. On most Linux systems, restart Apache with:

sudo service apache2 restart

or

sudo systemctl restart apache2

By following these steps, you can make Apache read and use your .htaccess file, allowing your RewriteRules to work as intended.

chmod 644 .htaccess

Enabling Rewrite Logging

To debug RewriteRule issues, you can enable rewrite logging in Apache. The process is different for Apache 2.2 and 2.4.

For Apache 2.2:

1. Add these lines to your virtual host configuration:

   RewriteEngine On
   RewriteLog "/path/to/rewrite.log"
   RewriteLogLevel 9

2. The RewriteLogLevel goes from 0 (no logging) to 9 (full logging).
3. Restart Apache to apply the changes.

For Apache 2.4:

1. The RewriteLog directive is not used.
2. Add this line to your configuration:

   LogLevel debug rewrite:trace8

3. This sets the logging level for the rewrite module to debug.
4. Restart Apache to apply the changes.

Analyzing Rewrite Logs

Understanding log levels:

• Lower levels (1-4) give basic information about rule matches and actions.
• Higher levels (5-9) give more details, including steps in the rewriting process.

Reading log entries:

1. Look for lines starting with "RewriteRule" or "RewriteCond" to see which rules are being applied.
2. Check the "pattern" and "substitution" parts of each rule to see if they match what you expect.
3. Look at [flags] at the end of rules, as they can change how the rule is applied.
4. Find lines showing successful matches or failed conditions to see where rules might be failing.

Set the log level back to a lower value after debugging, as high log levels can affect server performance.