Using Drush to Upgrade Drupal 6.x to Drupal 7.x

The drush site-upgrade command supports upgrades from Drupal 6.x to Drupal 7.x. Upgrades from Drupal 7.x to Drupal 8.x will be supported in the future. Use the drush pm-update command to do minor verison updates for Drupal 5.x, 6.x and 7.x.

To begin, consult the UPGRADE.txt file from the root folder of the version of Drupal you are upgrading to. Drush will handle some of the steps described there, but not all. In particular, you should make sure that your current Drupal installation is running on the most recent minor version available.

n.b. At the time of this writing, Drupal 6.20 and Drupal 7.0 were the most recent versions available. Always check primary sources prior to upgrading to see if anything may have changed.

Upgrade a Copy of your Site

Drush will always upgrade from the specified Drupal site to an empty Drupal site. It is necessary to create a site alias to describe the destination site. Site aliases are described in `drush topic docs-aliases`. A canonical site alias is adequate to define your target site for upgrade:

$aliases['onward'] = {
'root' => '/path/to/upgraded/drupalroot',
'uri' => 'http://onward.mysite.org',
}

Optionally, you might also want to define 'db_url' to specify the name of your target database. If you do not, drush will compose a database name for you based on the name of your site alias.

Running the `site-upgrade` Command

Drush will upgrade the current bootstrapped site, and will put the result in the target site specified by the argument to the command. For example:

drush @from site-upgrade @onward

The site-upgrade command will perform the following operations:

  1. Download the next major release of Drupal and store the files in the target site.
  2. Write a new settings.php file with an appropriate databases structure for the new target site.
  3. Make a copy of the SQL database for the new site.
  4. The default theme for the new site will be set to "garland", and the admin theme will be set to "seven".
  5. All non-core extensions will be disabled in the target database, and updatedb will be run on Drupal core.
  6. All of the modules disabled in the previous step will be downloaded again, if they have an appropriate version for the target Drupal site available.
  7. updatedb will be run again to update the non-core modules.
  8. All of the non-core modules will be enabled again.

When drush is enabling the modules in the upgraded site, if there are any new dependencies, they will also be identified and downloaded if possible. For example, views-7.x depends on the ctools module from the Chaos tool suite, whereas views-6 did not; drush will therefore download and enable ctools when upgrading the views module from Drupal 6 to Drupal 7.

There will still be some work left to do after the site-upgrade command has completed; for example, you will still need to port your theme and any custom modules to the new version of Drupal, and some contrib modules may require additional work to update their configuration settings. Using site-upgrade will all the same save you a considerable amount of time. There is no risk in trying it; if it does not work, you can always start over, or run it at a later date when more contrib modules have been updated.

Enjoy!