php - PrestaShop - Cannot login to back-office after upgrade (1.7.2.0 -> 1.7.7.4)

Solution:

Prestashop 1.7.7 is not compatible with PHP 7.4. Try downgrading it.

Solution:

This is a probably a cache issue.

Install the MyShopRepair on your server. Enable debug mode and click on the button "Clear cache".

After this you will have access to your shop again.