If the products in your store do not have a main photo set, and you need this photo - we have a way to do it. Operating on the database, in a few moments you will set the main photo for all products in your PrestaShop store.
Log in to your database, using for example phpMyAdmin. Then execute the following query:
UPDATE IGNORE `ps_image` SET `cover` = 1;
UPDATE IGNORE `ps_image_shop` SET `cover` = 1;
From now on, the first photo among all uploaded product photos will be the main photo.
The query works in PrestaShop 1.6.
If you need help with the development and operation of your PrestaShop - contact us. We will help you :-)