Backdrop CMS includes an update utility to handle any necessary changes to the database schema or configuration. Typically after replacing an older version of a module with a newer one, or the Backdrop core directory, you'll need to check if any updates need to be run.
About minor and major version updates
Backdrop CMS follows a semantic versioning scheme. Moving to the next minor (e.g. 1.1.y to 1.2.y) or patch version (e.g. 1.1.1 to 1.1.2) is considered an update. Moving the next major version (e.g. from 1.x.y to 2.x.y) is considered an upgrade and is a more involved process.
Minor and patch version updates maintain consistent APIs and can be done independently from any additional modules you may have installed on your site. Major version upgrades involve API changes that will usually require all the modules on your site to upgraded at the same time with compatible versions.
Updating between minor versions (1.0.x to 1.0.y or 1.1.y to 1.2.z)
Minor and patch updates are straight-forward and usually may be done independent of any module updates. It's usually a good idea to update Backdrop CMS core independently before attempting to do any module updates.
- Make a backup of your database.
- Make a backup of the config directory (it's located within the 'files' directory and begins with 'config_` unless otherwise specified in the settings.php file).
- Download the latest release of Backdrop CMS and extract it.
- Login to your site as a user with the "Administrator" role.
- (Optional but recommended) Put your site into maintenance mode.
- Rename the "core" directory in the root directory of your current codebase "core-old" or similar, and move it outside your Backdrop docroot.
- Put the new "core" directory from the latest release of Backdrop CMS inside your docroot.
- Run update.php by navigating to http://example.com/core/update.php
- If you turned on the maintenance mode option, turn it back off to make your site publicly accessible again.
- If all is well, delete the "core-old" directory.
Upgrading major versions of Backdrop CMS
Backdrop currently does not have any new major releases (e.g. a Backdrop 2.0), but the process will be the same for future releases as the current process for upgrading from Drupal 7.