I noticed somehow the following error:
[Mon Sep 05 10:24:38 2016] [crit] [client 192.168.1.1] (13)Permission denied: /home/user/public_html/.htaccess pcfg_openfile: unable to check htaccess file, ensure it is readable
Before the error occurred, I moved the files through sudo (from the root user) and to return the rights I executed the command:
sudo chown user:user -R /home/user/public_html
Which changed the owner to the one specified in all the subfolders and files, but the other directory should have been specified to the public_html directory (not its contents), because of which apache2 wrote that access was denied. Therefore, if you point to the public_html of the user and the group from which apache2 is running, the error disappears.
It can also be helped by specifying permissions 777 on this folder, it will give full access to all users (but this option is better not to use for security purposes).