Getting Started Guide

If anything goes wrong, the installer stops you here, enabling you to see
the few technical details that need fixing, be it changing the PHP
configuration or updating the file permissions.
While changing the PHP configuration can only be done on a case-by-case
basis depending on your level of access to your server, and therefore
cannot be explained here, updating the file permissions is easier to
explain. This will require you to access your remote files, and therefore
use your FTP client (such as FileZilla).
Log-in to your server account using your FTP client, browse to the
PrestaShop folder, and find the folders that are marked by the installer as
in need of a permission change.
CHMOD
Changing file/folder permission on a Unix/Linux system is called a
"CHMOD", after the command of the same name – you can find an
explanation of file permissions here). Giving them "write permission" is
called "doing a CHMOD 755" or "a CHMOD 775", depending on the host.
Some hosts might require you to use CHMOD 777, although it is not
recommended for anything more than a one-time need.
If you have to use CHMOD 777 in order to install PrestaShop, make
sure to switch to a safer setting (775, 755 or even 644) once you are
done installing.
In any case, thanks to FileZilla (and most FTP clients), you can change
permissions easily and graphically: once you have found a file or folder
that needs such a change, right-click on it from your FTP client, and in the
context menu choose "File permissions...". It will open a small window.