Knowing how to clear Drupal's cache is an important skill for any developer. You'll likely find yourself doing it frequently in order to get Drupal to register the changes you make to your code, or other updates you make via the UI. It is also a good first step to trouble shooting problems with your Drupal site: Clear the cache before you do any other debugging to ensure it's not just a bad cache entry.
Learn three methods of clearing Drupal's cache: via the administrative UI, with Drush, and by truncating tables in the database.
There are two common ways to clear Drupal's cache: via the UI, or with Drush.
Clearing the cache via the UI
Go to the Performance administrative page
In the Manage administrative menu, navigate to Configuration > Performance (admin/config/development/performance).
Select the "clear all caches" button
After successfully clearing the cache Drupal should display the message "Caches cleared."
Add Performance page to Shortcuts
Depending on your role, you may be clearing the cache a lot! Add the Performance page to your Shortcuts so that you can access the page more quickly. Click on the star icon next to the title, "Performance". The star icon will change from an outline of a star to a filled-in yellow star. Access Shortcuts via the Admin Toolbar.
Clearing the cache with Drush
To clear all caches, use the
drush cache-rebuild. This will empty all caches and rebuild the data required for Drupal to execute a page request. Alternatively, use the aliased commands
drush cr or
Open a Terminal window and
cd to your Drupal site root
If you're using Drush aliases, you can skip this step.
Run the command
drush cache-rebuild (
Wait for the command to successfully execute and return to your site.
Reload the page you were working on in your browser
It might take a bit longer than usual since the cache has been rebuilt.
What's the difference between cache-clear and cache-rebuild?
You may have been used to using "drush cc all" aka
drush clear-cache. Now it's
drush cache-rebuild or
drush cr, for short. What's the difference and why the change?
Caching is widespread in Drupal and creates many interdependencies. Improperly or incomplete cache flushing operations can cause the site to fatally error. In order to guarantee that old data is properly flushed and the site stays up and running,
drush cache-rebuild both rebuilds or re-bootstraps the Drupal site in addition to clearing the cache. Additionally, the Drush command cache is cleared with
drush cache-rebuild, since that was one of the caches included in the old
drush cache-clear command.
cache-rebuild command does the following:
- Clears the APC cache
- Bootstraps Drupal
- Clears the Drush cache (to maintain consistency with Drupal 7's drush cache-clear command)
If you'd like to take a peek under the hood of Drush's rebuild method, check out drush/src/Commands/core/CacheCommands.php (line 179).
Truncate cache-related database tables
Another method of clearing the cache is to truncate—or clear all the data from—the cache-related database tables. These are all the tables that begin with "cache_" (after the site-specific table prefix, if there is one).
In a SQL GUI application like Sequel Pro, which is what I like to use, this is easily accomplished by connecting to the server, selecting your site's database, highlighting all of the tables beginning with
cache_, ctrl-clicking and selecting Truncate tables. Confirm that you do when the alert pops up. Other database administrative programs will also have the ability to truncate tables.
Or, from the mysql CLI or a SQL command field in a database administrative tool (like PhpMyAdmin or others), you would run the following:
In this tutorial, you learned three methods for clearing Drupal's cache: via the administrative performance page at admin/config/development/performance, with
drush cache-rebuild or
drush cr, and by truncating cache_ tables in the database.
Further your understanding
- Now that you know how to rebuild Drupal's cache, learn how to turn off certain caches to work on theming and front-end development in Configure Your Environment for Theme Development.