How to make fields on the customer registration form in PrestaShop required
By default, in PrestaShop people have to register so that they can place orders. To do this they have to fill out a registration form on the frontend of your PrestaShop. Some of the fields are required (e.g. first and last name, email, address, etc.), and if the user doesn't type anything in these fields they can't register and become customers. The required fields are marked with a red asterisk (*).
If for whatever reason you need to do it, you can make other fields on the registration form required, fields that are optional by default. You can do this from the backend of your PrestaShop store. After you log in click on the Customers tab. At the bottom of the page that opens there's a button Set required fields for this section. This will display a table with field names; some of the fields in this table don't actually appear on the frontend's registration form. To make a field required simply mark the checkbox in front of its name and click on the Save button under the table. For example, if you mark the checkbox for the field birthday, the user will be required to specify their birth date in the appropriate field on the registration form (by default, the birthday field is not required).
To see other fields click on the Addresses sub-tab of the Customers main tab. At the bottom of the Addresses sub-tab page there's again a button Set required fields for this section. As with the other button just click on it to see the fields (as with the previous table not all of the listed fields appear on the registration form on the frontend). To make a field required mark its checkbox and click on the Save button.
Notice that when you use this method to make optional fields required they will not be marked with a red asterisk on the registration form on the frontend of your store. Despite this, the user will still be required to provide the necessary information in those fields. If you want to learn how to add a red asterisk to a field that you have made required, read the article on adding a red asterisk to a field on the registration form in PrestaShop
Keep in mind that the method described above is not for adding new fields to the registration form, but just for making fields that are already there required.