Drupal version numbering

This page explains Drupal's version numbering scheme for both Drupal core and contributed modules. It is designed to help you understand what the various version numbers mean and how you can use this information when building a Drupal site.

Which version of Drupal core should I run?

In brief, you should always run one of the recommended official releases. These can be found at the Drupal Project page.

At any given time, there are two major release series of Drupal which are supported. Currently, these are Drupal 5 and Drupal 6. Updated versions of each of these are issued on a regular basis. For example, within the Drupal 6 series, several versions have been and will continue to be released: 6.0, 6.1, 6.2, etc. These versions are sometimes collectively referred to as "6.x"; however, they are not all equal. The newest version in each series fixes problems that were discovered since the previous version, and these fixes sometimes include critical security updates. Thus, regardless of whether you are using Drupal 5 or 6, you should always run the most current version in the series.

In deciding between Drupal 5 and Drupal 6, several factors should be taken into consideration. Drupal 6 is newer, will be supported longer, and contains more features and enhancements than Drupal 5; therefore, if all else is equal, use Drupal 6. However, the releases of contributed modules, themes, and translations compatible with each major Drupal release series sometimes lag behind Drupal itself, so if the functionality you need is not yet available for Drupal 6, this may affect your decision. (The contributed module status list is a useful reference, although you should always verify the information there with the module's official project page.)

Drupal 7 is currently under development and is not yet fit for production use. If previous patterns continue, a stable version (Drupal 7.0) will likely be released sometime in 2009. Once that happens, Drupal 5 will no longer be supported or receive security updates, and you will need to update your Drupal 5 sites to Drupal 6 at that time.

Which version of contributed modules, themes, and translations should I run?

You usually should run one of the "official releases" from the module, theme, or translation's project page, because these are the versions that are currently supported by the maintainer. Note that when examining a particular release available on these pages, the first part of the version number shows you which major release series of Drupal core a module, theme, or translation is compatible with. For example, a module with a version number of 5.x-1.2 will only work with Drupal 5, whereas a module with a version number of 6.x-1.2 will only work with Drupal 6.

When is the next release?

Per the Open Source tradition, when it's ready. When sufficient testing of fixes of bug reports is complete. More attention is given to a rapid release of security issues. The more people involved in fixing and testing reported issues, the faster a release is likely to come out.

How do I know which version of Drupal I'm running?

If it's available, go to Administer >> Reports >> Status report. This will list your version number if you have Drupal 6.0 or later. In Drupal 5.x and earlier, the path to go to is Administer >> Logs >> Status report.

Failing that, look for a file called CHANGELOG.txt in the root of your Drupal directory and open it up to find the version you are running.

If CHANGELOG.txt is missing, you can also check in system.module for a line at the top like:

define('VERSION', '5.5');

If this is present, it will tell you which version you are running. If not, you have a version earlier than 4.7.2.

How do I know which version of a module or theme I'm running?

You can see the versions of your installed modules and themes on the modules and themes administration screens. Go to Administer >> Site building >> Modules or Administer >> Site building >> Themes, and you will see a column listing the version number.

What about upgrading and backwards compatibility?

For more details read this overview of the Drupal's philosophy on backwards compatibility.

More details

The pages below have some more details for advanced users.