System requirements

Web Server

Recommended: Apache

• Drupal will work on Apache 1.3 or Apache 2.x hosted on Unix/Linux or Windows. The majority of Drupal development is done using Apache so there is more community experience and testing performed.
• You can use the Apache 'mod_rewrite' extension to allow for clean urls.

Microsoft IIS

• Drupal core will work using IIS5 or IIS6 if PHP is configured correctly. In view of Microsoft's support life cycle it is suggested you use IIS6.
• To achieve clean_url's you will need to use a third party product.

Drupal is being developed to be web server independent but we have limited or no reports of successful use on web servers not listed here.

PHP

Recommended: PHP 5.2 or higher
Required: PHP version 4.3.5 or higher

• PHP 5.2 or higher is only supported by Drupal 4.7.5 or higher and Drupal 5.1 or higher.
• PHP 5.2 or higher will be a requirement for Drupal 7.
• PHP memory of 16MB or higher for a default Drupal 6 installation (8MB or higher may be sufficient for default installations of earlier versions). Depending on your site's use of custom or contributed modules, your PHP memory limit may need to be increased beyond 16MB. (See the Increase PHP memory limit page in the Troubleshooting FAQ for additional information on modifying the PHP memory limit.)
• The PHP extension for connecting to your chosen database needs to be installed and enabled. Drupals currently supported database connectors are: mysql (the original MySQL extension), mysqli (an improved connector for newer MySQL installations), and pgsql (for PostgreSQL). Note: PHP 5.x no longer enables the mysql extension by default. Please read the links above for installing and enabling your chosen connector. Additionally, Drupal 6.x does not provide the option to select the mysql connector if mysqli is enabled in your PHP configuration.
• PHP XML extension (for blogapi, drupal, and ping modules). This extension is enabled by default in a standard PHP installation; the Windows version of PHP has built-in support for this extension.
• An image library for PHP such as the GD library is needed for image manipulation (resizing user pictures, image and imagecache modules). GD is included with PHP 4.3 and higher and enabled by default. ImageMagick is also supported for basic manipulations in Drupal core but support in the contributed modules repository is much less developed.
• PHP needs the following configuration directives for Drupal to work (only directives that differ from the default php.ini-dist / php.ini-recommended):
  • session.save_handler: user
  • error_reporting set to E_ALL & ~E_NOTICE. Work is ongoing to change this to E_ALL for Drupal 6.
  • In addition, we recommend the following setting: session.cache_limiter: nocache
• Some of these settings are contained in the default .htaccess file that ships with Drupal, so you shouldn't need to set them explicitly. Note, however, that setting PHP configuration options from .htaccess only works:
  • with Apache (or a compatible web server)
  • if the .htaccess file is actually read, i.e. AllowOverride is not None
  • if PHP is installed as an Apache module
• See the PHP manual for how to change configuration settings for other interfaces to PHP.
• In some shared hosting environments, access to these settings is restricted. If you cannot make these changes yourself, please ask your hosting provider to adjust them for you.

Database Server

Recommended: MySQL 4.1 or MySQL 5.0

• Drupal 6 supports MySQL 4.1 or higher.
• Drupal 5.x and earlier supports MySQL 3.23.17 or higher. MySQL 4.1 or higher is strongly recommended.
• NOTE: Drupal makes use of some features not available on some inexpensive hosting plans so please check that your host allows database accounts with the following rights:
  SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, INDEX, ALTER, CREATE TEMPORARY TABLES, LOCK TABLES

As of 6.x, Drupal core no longer requires CREATE TEMPORARY TABLES or LOCK TABLES, and can be installed without them. However some contributed modules may still rely on them.

Note: If your system/host is running MySQL 4.1 or newer and you receive the error "Client does not support authentication protocol requested by server", address the problem by following the instructions provided by MySQL AB. There is a minor OS issue with some MySQL 5+ installations primarily on Windows but affecting some versions of Unix/Linux as well.

PostgreSQL 7.4 or higher

• Note: Some contributed modules are not as abstracted from MySQL specific code as everyone would like. If you are familiar with PostgreSQL please file issues with those contributed modules as you find them.

Currently MS SQL and Oracle are not supported but various efforts are underway to supply schemas. Please see discussions in the Enterprise Group if you are interested in working on this.