What changes in CartRule.php between PrestaShop 9.0.x and 9.1.x?
PrestaShop 9.1.x introduces the foundations of a new Discount system inside CartRule.php, protected by a feature flag.
That sounds safe at first — and it is, because backward compatibility is preserved while the flag is disabled. But once enabled, several important behaviors change, especially around discount typing, ORDER_LEVEL calculation, shipping inclusion, and compatibility rules. (nicolas-dabene.fr)
In my full write-up, I compare 9.0.x and 9.1.x in detail and explain what PrestaShop module developers should watch before supporting both versions safely.
Read the full article:
https://nicolas-dabene.fr/en/articles/2026/03/05/evolution-cartrule-prestashop-9/