Below you find some additional notes regarding the PHP requirements for Drupal. Individual modules may have specific requirements and configurations needed, please double check module documentation as well. Within the Drupal interface, it is highly recommended that caching be enabled under admin/config/development/performance. This will help increase the performance of your Drupal installation and the end user experience. For more details see Caching to improve performance.
On this page:
- PHP sources
- File and Folder Permissions
- PHP Configuration Settings
- Recommended PHP configuration settings
- Memory requirements
- Drupal specific version notes on PHP requirements
PHP from different sources
Drupal is designed to work with PHP as distributed on php.net. Every effort is made to make it work with PHP versions from other sources but this is only done on a best effort basis. In particular, suhosin is known to break certain features and some operating systems move core components into other packages.
File and Folder Permissions
PHP Configuration Settings
- error_reporting set to E_ALL & ~E_NOTICE. Work is ongoing to change this to E_ALL for Drupal 6 and Drupal 7.
- safe_mode: off. Safe mode may interfere with file and image uploads. This is applicable for only for PHP version's below 5.3.0, as of PHP 5.4.0 Safe Mode has been removed
- Tokenizer functions require the tokenizer extension to be enabled. (Read more )
Recommended PHP configuration settings
Setting: session.cache_limiter = nocache
Setting: session.auto_start = 0
Setting: expose_php = off
Reason: Shows current PHP version in all header requests, security disclosure, see here
Example: X-Powered-By: PHP/5.3.8
Setting: allow_url_fopen = off
Reason: This is a security issue: see here
Setting: magic_quotes_gpc = off
Reason: Forces quotes in variables - This feature has been deprecated as of PHP 5.3.0 and removed as of PHP 5.4.0.
Setting: register_globals = off
Reason: Security issue - having this enabled subjects PHP variables to input from any source:
This feature has been deprecated as of PHP 5.3.0 and removed as of PHP 5.4.0.
Setting: display_errors = Off
Reason: Hides errors output to display (website) we want to send to log file instead.
PHP memory requirements can vary significantly depending on the modules in use on your site.
- Drupal 6 core requires PHP's memory_limit to be at least 16MB.
- Drupal 7 core requires 32MB.
- Drupal 8 core requires 64MB.
Note that Drupal 8 uses extensive
lazy loading of code and data. Slight differences from page to page can produce huge differences in memory usage. Check memory usage for each type of page and view. The administration pages should produce the worst cases.
Warning messages will be shown if the PHP configuration does not meet these requirements. However, while these values may be sufficient for a default Drupal installation, a production site with a number of commonly used modules enabled could require more memory. Typically 128 MB or 256 MB are found in production systems. Some installations may require much more, especially with media-rich implementations. If you are using a hosting service it is important to verify that your host can provide sufficient memory for the set of modules you are deploying or may deploy in the future. (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 must be installed and enabled. Drupal's 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 Blog API, 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. Enabling the XML extension also enables PHP DOM. DOM is now a systems requirement.
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 usually enabled by default. GD is a required extension in Drupal 7 and later. ImageMagick is also supported for basic image manipulations in Drupal core but there is much less support from contributed modules.
If you have administrator rights on a Debian/Ubuntu server, and GD is not already available (see your phpinfo) it can usually be installed by running the following command:
sudo apt-get install php5-gd
or on Redhat/Centos:
sudo yum install php-gd
See the ImageMagick install instructions for your platform if you want that.
Drupal 7 and 8 require PHP compiled with JSON. JSON support is normally compiled as part of PHP core, but in case you're getting errors like
PHP Fatal error: Call to undefined function Drupal\\Component\\Serialization\\json_encode() in ... core/lib/Drupal/Component/Serialization/Json.php try adding the JSON extension.
Recent versions of APC (apparently since 3.1.6) set 'Enable internal debugging in APC' as the default. This generates large numbers of PHP messages that can make diagnosing other problems more difficult. This option can be disabled during installation by explicitly entering
no to the prompt - hitting 'enter' will enable the option in spite of the wording of the prompt.
Also see Drupal 7-specific information relating to APC.
Some of the memory 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 under the following conditions:
- With Apache (or a compatible web server)
- If the .htaccess file is actually read, i.e. AllowOverride All in the main Apache configuration (usually httpd.conf) is enabled
- If PHP is installed as an Apache module
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.
See the PHP manual for how to change configuration settings for other interfaces to PHP.
If using xdebug:
Setting: xdebug.show_exception_trace = 0
Reason: Could cause Drupal's installer to crash
If using xdebug with Drupal 8:
Setting: xdebug.collect_params = ?
Reason: Setting xdebug.collect_params too high will prevent Drupal 8 from installing and working properly.
Setting: xdebug.max_nesting_level = 256
Reason: Using the default max_nesting_level of 100 (in xdebug versions < 2.3) causes some pages to crash.
Drupal specific version notes on PHP requirements
On Debian libapache2-mod-php5filter may get installed in preference to libapache2-mod-php5 (http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=709027). Unfortunately the libapache2-mod-php5filter package has a bug which breaks Drupal - http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=709023
So, make sure you specify to use the libapache2-mod-php5 package instead.
|PHP version||Drupal 6||Drupal 7||Drupal 8|
|4.4||yes, no support||no||no|
|5.3||core ok, modules with warnings||yes||no|
|5.4||core ok, modules may fail||yes (minimum recommended)||5.4.5+|
Drupal 8 requires version PHP 5.5.9 or later, with the CURL extension.
Debian currently ships with 5.4.4 and produces an obscure error. For Debian, the minimum patch level is 5.4.4-14. There is an issue open, https://www.drupal.org/node/2267551, to make the minimum requirement 5.4.5.
If your curl library is version 7.35 (the default on some ubuntu distibutions), there is a bug that could intermittently affect connectivity with other sites.
Drupal 8 will also works with PHP 7.0.
Drupal 8 can no longer be installed on hosts with the 'magic_quotes_gpc', 'magic_quotes_runtime', or 'safe_mode' PHP ini settings turned on; these settings are deprecated in PHP 5.3 and have no effect anymore in PHP 5.4.
If using the APC opcode cache with Drupal 8, APC 3.1.13 or greater is required. PHP 5.5 has the Zend opcode cache built in.
php5-ctype is required.
The following PHP requirements list is from Drupal 8 beta 1.
$required_extensions = array(
- The standard PHP extensions (enabled by default) Hash and JSON are required by Drupal 7.
- Drupal 7 Update manager can install/update modules and themes via SSH if the required libraries have been installed on the server. If you have administrator rights on a Debian/Ubuntu server, and SSH is not already available (see your phpinfo) it can usually be installed by executing:
apt-get install libssh2-php.
- PHP Data Objects (PDO) must be activated for Drupal 7 to install and run correctly. Look in your php.ini. Uncomment (remove the leading semicolon) at line
extension=php_pdo_mysql.dll. In Linux, these would be
extension=pdo_mysql.so. Some Linux distributions may have these extensions by default in files found in the conf.d folder (Ubuntu 12.04:
pdo_mysql.ini). If these lines are not there, you will need to add them. The PECL version of PDO is not compatible with Drupal 7 and cannot be used.
- Drupal 7 may require the time parameter (
max_execution_time) to be at least 30 seconds.
- Opcode caching may prevent Drupal 7 from completing the install of all database tables, often referred to as the '31 Tables' problem (reported in Drupal 7 Install Problems). PHP 5.5's built-in opcode cache can be disabled through
sudo php5dismod opcachefollowed by a restart of Apache. Once the install is complete, the opcode cache can be re-enabled with
sudo php5enmod opcache, again followed by a restart of Apache.
- APC installation guides sometimes recommend setting
apc.include_once_override=1. Although this setting does not appear to affect Drupal 6, it causes Drupal 7 to fail (white screen, error 500) as reported in Do not enable apc.include_once_override.
Drupal 7: PHP 5.2.5 * (5.4 or higher recommended).
*For Drupal 7, versions of PHP 5.2.4 that include backported security patches also meet the requirements. The PHP version included with Ubuntu 8.04 is the most common example of this.
See the phpinfo() page on Drupal.org to learn how to use phpinfo to get the details of your system. For example, phpinfo will tell you if you have a database already installed and what versions of PHP, MySQL, etc. your system is running. Phpinfo will also tell you what PHP variables are set as well as many other helpful things.
Drupal 6 is currently supported on PHP 4.4+, however we announced dropping PHP 4.x support altogether on March 1st, 2014.
Although PHP 5.3 is supported by Drupal 6, some contributed modules may not be compatible with PHP 5.3, and some PHP 5.3 configurations still show warnings with Drupal 6.14. Work is ongoing to resolve the latter in. Most Drupal 6 contributed modules throw E_STRICT errors on PHP 5.3 and many are practically unusuable on 5.4.