How do I find out which PrestaShop version I am running?

You can find the PrestaShop version in the Back Office footer, in Advanced Parameters > Information, and in the codebase via app/AppKernel.php or config/settings.inc.php depending on version. In modules, _PS_VERSION_ is the runtime constant used for compatibility checks.

grep -R "_PS_VERSION_" config/settings.inc.php app/AppKernel.php 2>/dev/null
php -r 'require "config/config.inc.php"; echo _PS_VERSION_, PHP_EOL;'

For day-to-day admin work, the back-office footer and Advanced Parameters > Information are the safest places because they show the version of the running shop. For code checks, newer PrestaShop versions commonly expose the version through AppKernel, while older installations may define it in config/settings.inc.php. A module's own version number is not the PrestaShop version; it only identifies that module release.

For PrestaShop 1.6, the filesystem check is usually config/settings.inc.php, where _PS_VERSION_ is defined. For PrestaShop 1.7 and 8, app/AppKernel.php commonly exposes the application version used by the running shop. On any generation, the back-office footer and Advanced Parameters > Information are better than guessing from a copied file because they reflect the installed shop that actually booted.

If you maintain several shops, also check the admin URL you are logged into before reading the footer: a staging shop, production shop and restored backup can have different versions even when they share similar files or database names.

If you are checking compatibility before installing or upgrading a module, use the running shop version and compare it with the module's declared compatibility range. In custom module code, use version_compare(_PS_VERSION_, 'x.y.z', '>=') style checks instead of hard-coding assumptions from a file path. After a major upgrade, clear cache and confirm the back office reports the expected version, because stale files or an incomplete deployment can make filesystem checks misleading.