Managing Drush Versions on Pantheon

Learn about Pantheon's default Drush version and how to implement site-local usage.

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By default, Pantheon runs Drush 8 on newly created Drupal sites.

Terminus Drush and Local Drush

Terminus makes remote Drush calls on sites without using a local installation, eliminating compatibility issues between local and remote installs. For more information, see our guide on Managing Drupal Sites with Terminus and Drush.

Available Drush Versions

Pantheon currently supports Drush versions 8, 9, and 10.

Drush 8 is the preferred version of Drush to use with Drupal 8 sites that are managed by Composer. See Drupal 8 and Composer on Pantheon Without Continuous Integration and the Build Tools Workflow for information on how to use Composer to manage Drupal sites on Pantheon.

Drush 8 should also be used for Drupal 8 sites that are not managed by Composer, or that use modules that provide additional Drush 8 commands.

Verify Current Drush Version

Verify the current version of Drush running on Pantheon using Terminus:

terminus drush <site>.<env> -- status | grep "Drush version"

Configure Drush Version

Before you modify a site's Drush version, remember that not all versions of Drush are compatible with all versions of Drupal. See Available Drush Versions and the requirements below.

Change a site's Drush version via the pantheon.yml file:

api_version: 1

drush_version: 8

Now your site’s Drush version is managed via pantheon.yml, so it’s in version control and deployed along with the rest of your code.


If the pantheon.yml file does not exist, create it. If a pantheon.upstream.yml file exists, do not edit it. It is used by the upstream updates repository and will cause a merge conflict if modified.

Compatibility and Requirements

Drush 8 is compatible with Drupal 6, 7, and 8.

Always use Drush 8 with Drupal 7 and Drupal 6 sites, as Drush 9 and Drush 10 only work on Drupal 8.4 and later.

While Drush 5 and Drush 7 are available on Pantheon if needed, they are listed as unsupported by the Drush maintainers, and should be avoided unless absolutely necessary.

Drush 10 is available with the addition to your pantheon.yml file shown above, or for site-local installation. It requires Drupal 8 or higher, Composer, and PHP 7.1 or higher.


When running Drush locally, we highly recommend running Drush version 8.3.2 or higher.

PHP Requirements

Drush VersionMinimum PHP Version
Drush 5PHP 5.2.0+
Drush 7PHP 5.3.0+
Drush 8PHP 5.4.5+
Drush 9PHP 5.6.0+
Drush 10PHP 7.1.+

See our guide on Upgrading PHP Versions.


Sometimes, even after updating the Drush version in pantheon.yml, the correct version of Drush is not called.

The Pantheon platform always prefers the site-local Drush or other local settings over the setting in pantheon.yml. Check for an outdated configuration file,, in your local ~/.drush directory. Remove the file, or comment out its contents to resolve.

Executing Drush on the platform via a terminus drush command will use the version of Drush specified in pantheon.yml, unless a site-local version is present.

Site-local Drush Usage

If you need to specify a minor version or a version not available on the platform, you can add a site-local installation of Drush to your repository.

In general, you will usually be better off not including a site-local Drush in your Pantheon site, as using the Pantheon-provided Drush ensures that you are using the recommended and most-tested version for the Pantheon platform. Occasionally, using a site-local Drush may be necessary in order to avoid conflicts with your site's dependencies.

Do not select any major version of Drush lower than 8.3.2, 9.7.1, or 10.2.0.

For more information, see Avoiding “Dependency Hell” with Site-Local Drush.


Site-local Drush needs executable permissions. If you encounter "permission denied" errors when running Drush commands, adjust permissions on the Drush executable:

chmod +x vendor/bin/drush

Then commit and push this change back up to your Pantheon site.

Drush 5 on Older Sites

Drupal sites created on Pantheon in late 2015 or earlier that do not have drush_version defined in pantheon.yml may default to Drush 5. In this case, you may see the following error:

{{Uncaught Error: Call to undefined function mysql_connect() in /etc/drush/drush-5-extensions/

Configure a newer version of Drush as documented above to resolve.

See Also