Also known as front office not working after installation.
First thing after installing PrestaShop was this error. Back-end works fine (or at least looks ok) but front-end does not open. And it may be super annoying if you have worked with trouble free WooCommerce before.
Solution turned out to be very simple:
Turning on SSL (to get all redirections work) if you have SSL. Shop Parameters → General
Clearing cache and turning all cache off during initial build-up and development. Advanced Parameters → Performance
Figuring it out took few hours and bunch of nerves.