“Page Not Found” Errors on every page except homepage.

UPDATE for Drupal 8 / PHP 7.2 / Ubuntu 18.04

1 Enable mod_rewrite as described below

2 Add the following to 000-default.conf as follows:

Use below process to enable clean url with Ubuntu 16.04:

1. Enable apache mode rewrite –

   a2enmod rewrite 

2. put below code into /etc/apache2/sites-available/000-default.conf

   <Directory /var/www/html> Allowoverride All </Directory> 

3. service apache2 restart

The most likely cause is misconfiguration of mod_rewrite or clean URLs on the new server. Confirm this by short-circuiting the clean URL system and requesting pages directly, like this:

http://www.example.com/index.php?q=user

If the login page is shown, then you can assume that Drupal’s page serving mechanism is working properly, but mod_rewrite isn’t working. To determine if mod_rewrite is enabled, create a file called phpinfo.php in the root of your site. This file should be accessible from a web browser and contain this code:

phpinfo(); 

Ensure that mod_rewrite is enabled

Navigate to phpinfo.php in a browser like this: http://www.example.com/phpinfo.php

On that page, look for a section called “Loaded Modules” and check that mod_rewrite is included. If not, mod_rewrite is not being loaded by apache and will need to be enabled. The process will be different depending on the server platform and apache build. Keep the phpinfo.php file for now – it will be helpful later.

Step 1 — Enabling mod_rewrite

In order for Apache to understand rewrite rules, we first need to activate mod_rewrite. It’s already installed, but it’s disabled on a default Apache installation. Use the a2enmod command to enable the module:

• sudo a2enmod rewrite

This will activate the module or alert you that the module is already enabled. To put these changes into effect, restart Apache.

• sudo systemctl restart apache2

mod_rewrite is now fully enabled. In the next step we will set up an .htaccess file that we’ll use to define rewrite rules for redirects.

Step 2 — Setting Up .htaccess

An .htaccess file allows us to modify our rewrite rules without accessing server configuration files. For this reason, .htaccess is critical to your web application’s security. The period that precedes the filename ensures that the file is hidden.

Note: Any rules that you can put in an .htaccess file can be also put directly into server configuration files. In fact, the official Apache documentation recommends using server configuration files instead of .htaccess because Apache processes it faster that way.

However, in this simple example, the performance increase will be negligible. Additionally, setting rules in .htaccess is convenient, especially with multiple websites on the same server. It does not require a server restart for changes to take effect and it does not require root privileges to edit those rules, simplifying maintenance and and making changes possible with unprivileged account. Some popular open-source software, like WordPress and Joomla, often relies on an .htaccess file for the software to modify and create additional rules on demand.

Before you start using .htaccess files, you’ll need to set up and secure a few more settings.

By default, Apache prohibits using an .htaccess file to apply rewrite rules, so first you need to allow changes to the file. Open the default Apache configuration file using nano or your favorite text editor.

• sudo nano /etc/apache2/sites-available/000-default.conf

Inside that file, you will find a <VirtualHost *:80> block starting on the first line. Inside of that block, add the following new block so your configuration file looks like the following. Make sure that all blocks are properly indented.

<VirtualHost *:80> <Directory /var/www/html> Options Indexes FollowSymLinks MultiViews AllowOverride All Require all granted </Directory> . . . </VirtualHost> 

Save and close the file. To put these changes into effect, restart Apache.

• sudo systemctl restart apache2

Now, create an .htaccess file in the web root.

• sudo nano /var/www/html/.htaccess

Add this line at the top of the new file to activate the rewrite engine.

RewriteEngine on 

Save the file and exit.

You now have an operational .htaccess file which you can use to govern your web application’s routing rules. In the next step, we will create sample website files that we’ll use to demonstrate rewrite rules.

Step 3 — Configuring URL Rewrites

Here, we will set up a basic URL rewrite which converts pretty URLs into actual paths to pages. Specifically, we will allow users to access http://your_server_ip/about, but display a page called about.html.

Begin by creating a file named about.html in the web root.

• sudo nano /var/www/html/about.html

Copy the following HTML code into the file, then save and close it.

<html> <head> <title>About Us</title> </head> <body> <h1>About Us</h1> </body> </html> 

You can access this page at http://your_server_ip/about.html, but notice that if you try to access http://your_server_ip/about, you will see a 404 Not Found error. To access the page using /about instead, we’ll create a rewrite rule.

All RewriteRules follow this format:

RewriteRule pattern substitution [flags] 

• RewriteRule specifies the directive.
• pattern is a regular expression that matches the desired string from the URL, which is what the viewer types in the browser.
• substitution is the path to the actual URL, i.e. the path of the file Apache servers.
• flags are optional parameters that can modify how the rule works.

Let’s create our URL rewrite rule. Open up the .htaccess file.

• sudo nano /var/www/html/.htaccess

After the first line, add the RewriteRule marked in red and save the file.

RewriteEngine on RewriteRule ^about$ about.html [NC] 

In this case, ^about$ is the pattern, about.html is the substitution, and [NC] is a flag. Our example uses a few characters with special meaning:

• ^ indicates the start of the URL, after your_server_ip/.
• $ indicates the end of the URL.
• about matches the string “about”.
• about.html is the actual file that the user accesses.
• [NC] is a flag that makes the rule case insensitive.

You can now access http://your_server_ip/about in your browser. In fact, with the rule shown above, the following URLs will point to about.html:

• http://your_server_ip/about, because of the rule definition.
• http://your_server_ip/About, because the rule is case insensitive.
• http://your_server_ip/about.html, because the original proper filename will always work.

However, the following will not work:

• http://your_server_ip/about/, because the rule explicitly states that there may be nothing after about, since the $ character appears after about.
• http://your_server_ip/contact, because it won’t match the about string in the rule.

You now have an operational .htaccess file with a basic rule that you can modify and extend to your needs. In the following sections, we will show two additional examples of commonly used directives.