How to Fix Apache 404 Not Found on Debian 11

The Root Cause: On Debian 11, “Apache 404 Not Found” errors frequently occur because the mod_rewrite module, essential for handling “pretty URLs” in many modern web applications, is not enabled by default. Additionally, Apache’s default AllowOverride None directive in its configuration can prevent .htaccess files (which commonly contain URL rewrite rules) from being processed.

Quick Fix (CLI): This quick fix addresses the scenario where mod_rewrite is not enabled.

sudo a2enmod rewrite
sudo systemctl restart apache2

Configuration Check: If the Quick Fix doesn’t resolve the 404, the issue likely lies in Apache’s inability to process .htaccess files, or an incorrect DocumentRoot setting.

1. Verify DocumentRoot: Edit your virtual host configuration file, typically found at /etc/apache2/sites-available/your-site.conf (replace your-site.conf with your actual site’s file, e.g., 000-default.conf). Ensure the DocumentRoot directive accurately points to the directory containing your website’s files.

   # Example: /etc/apache2/sites-available/your-site.conf
   <VirtualHost *:80>
       ServerAdmin webmaster@localhost
       DocumentRoot /var/www/html/your-application-directory # <-- Confirm this path
   
       ErrorLog ${APACHE_LOG_DIR}/error.log
       CustomLog ${APACHE_LOG_DIR}/access.log combined
   </VirtualHost>

2. Enable .htaccess processing (AllowOverride): Within your virtual host configuration file (/etc/apache2/sites-available/your-site.conf), locate or add a <Directory> block that matches your DocumentRoot. Inside this block, change AllowOverride None to AllowOverride All. This enables .htaccess files for that directory.

   # Example: /etc/apache2/sites-available/your-site.conf
   <VirtualHost *:80>
       ServerAdmin webmaster@localhost
       DocumentRoot /var/www/html/your-application-directory
   
       <Directory /var/www/html/your-application-directory> # <-- Match your DocumentRoot
           Options Indexes FollowSymLinks
           AllowOverride All # <-- Change this from None to All
           Require all granted
       </Directory>
   
       ErrorLog ${APACHE_LOG_DIR}/error.log
       CustomLog ${APACHE_LOG_DIR}/access.log combined
   </VirtualHost>

   After making changes, always restart Apache to apply them:

   sudo systemctl restart apache2

Verification: After applying any fixes, confirm Apache’s status and attempt to access the URL that was previously returning a 404.

sudo systemctl status apache2
curl -I http://your-domain.com/path/to/resource

A successful fix will display an HTTP status code other than 404 Not Found (e.g., 200 OK or 301 Moved Permanently).