Prestashop lot of error fixed by this. 
Installed module and site  prestashop and 502 Bad Gateway error displayed

This is a module that we really think should be Prestashop standard function. Let me explain why this is a MUST HAVE MODULE, if you make changes on your frontend now and then

This one of the best module to Change the currency symbol and position with language .

 you need to change the dollar symbol into any other symbol or letter add in module configuration.

This module will help you keep your store nice and clean. Fix bugs, improve performance, make your backups smaller and upgrade process much faster with excessive data removed from you database.

Prestashop CMS page gallery and store details with easy short code implementation. Prestashop CMS Shortcode Gallery module comes with one click installation and gives flexibility to place these short codes anywhere in your CMS pages. You can place multiple gallery in one pages and/or you can place same gallery accross the many CMS pages using a simple shortcode.

Customize your Prestashop site’s appearance by easily adding custom CSS and JS code without even having to modify your theme or plugin files. This is perfect for adding custom CSS tweaks to your site.

Prestashop lot of error fixed by this. 
This code solved DisplayPositions getting Error 500 , Prestashop module postions error fixed.

Display Featured Products by category Home page Product page bottom and every page left right column with responsive and slider. Best module to Show product's

Google Tag Manager  module allows you to integrate Google Tag Manager on your PrestaShop site so that you can track and gather valuable visitor data from your website and make...

Google Language Translator is the best PrestaShop Translation module available for translating your website into over 105  different languages. simple install and working

Fast and optimized pages lead to higher visitor engagement, retention, and conversions. Increase page load speed.
The Page Speed Module help you to get a passing grade in Google Page Speed Insight.

GZIP compression is bundling (zipping) pages on a web server before the page is sent to the visitor.This saves bandwidth and therefore increases the loading speed of the page significantly.