Here is a excellent tutorial show you how to Solve nginx Error 413 Request Entity Too Large:
Changing your php.ini-settings alone won’t do much. So to fix this problem, follow these steps.
Open up your nginx.conf-file, with an editor of your choice:
vim /etc/nginx/nginx.conf..and add client_max_body_size to the http-section:
client_max_body_size 20M;Save and close the file, apply the changes to nginx, and reload:
/usr/sbin/nginx -t /usr/sbin/nginx -s reload