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• /mails folder has all the mails that you have modified.
  If you have never made any modification there, do not worry about this folder.
• /img folder contains your logo and all the pictures of your store (categories, products…)
• /modules folder, only copy the modules that you have added.
• /themes/yourtheme folder, only copy your current theme. If you use the default theme from PrestaShop, do not copy it, you must use the one from the new version.
• /download and /upload folders, which contain all the downloadable products, the attached files and the customizable products. If you do no use any of these functionalities, do not copy these folders.
• /classes folder: in case you have added customized classes to this folder, copy them to the new /classes folder.
  In order to function properly with the latest version of PrestaShop, all these class files need to have their class name suffixed with "Core":
  • Open each and every one of the class files, and find the ones where the class name is not Core-prefixedsuffixed. If you are upgrading from PrestaShop 1.4.x, you shouldn't have any (except for custom classes).
  • Rename the class name, adding the "Core" suffix. For instance, "MyClass" becomes "MyClassCore".
    Only change the name in the PHP class within file, not the name of the file itself.!
  • If all the files already have "Core" in their classname (such as "class AttributeCore extends ObjectModel"), then you do not need to change anything.
  • Save the edited files.
• /config folder, only copy the settings.inc.php file, then modify the following lines:
  • The line that contains "PS_BASE_URI" must contain the name of the subfolder where you are going to do your update. For instance, "/prestashop/" instead of "/", or of the name of current folder for your current store.
  • If you modified your database credentials (you should not have had to do that normally), update all the lines that contain "DB_NAME", "DB_USER" and "DB_PASSWD" too.

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