PrestaShop does not save product changes in Back Office

It is an issue in the PrestaShop Back Office product page when you try to save a product (clicking save or save and stay button) and the product sometimes is saved and sometimes the page is just reloaded without product saving.

To resolve this issue we need to make some fix in the PS backoffice template.

For this open the file: 

/your store folder/your admin folder/themes/default/template/controllers/products/helpers/form/form.tpl

And in this file remove or comment the code:

submitHandler: function(form) {
 form.submit();
},