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.
- An Update is 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).
- An Upgrade is moving the next major version (e.g. from 1.x.y to 2.x.y) 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, which will usually at the same time require that all the modules on your site are upgraded to compatible versions.