During the installation process of Prestashop 1.7, we may encounter an error. The Prestashop team has indicated that this error will be fixed in future revisions.
The way to install it without problems right now would be:
Install it from Plesk or from the installation package downloaded from the Prestashop website, in English language.
Once installed, we should change the language to Spanish.
To do this, we go to the side menu:
(Prestashop 1.6) Localization -> Localization
(Prestashop 1.7) International -> Localization
Once in this window, we go to "Localization pack you want to import" and look for Spain.
We must have selected Taxes, Currencies, Languages, Units.
We click on Import.
In that same window we can see that there is a section for Configuration, we will put the following configuration:
Default language Spanish
Default Country Spain
Default currency Euro
Time zone Europe/Madrid
Once this is done, we go to our user and click on My preferences.
In Language, we select Spanish and we will have our Prestashop installed correctly, avoiding said error.