Memo:

for nginx people
if you have php-fpm installed you have to tell it that its user and group is nginx. /etc/php-fpm.d/www.conf . find user which is assigned to apache by default and change it to nginx. also do it for group. then run this command :

sudo service php-fpm restart

also inside of your wordpress directory execute these commands

sudo chown nginx:nginx * -R 
sudo usermod -a -G nginx username

change username into what your current username is.

yet you have to apply propper permissions. run these commands inside your wordpress directory

sudo find . -type f -exec chmod 664 {} + 
sudo find . -type d -exec chmod 775 {} +