on /etc/nginx/nginx.conf add the following line to server or location or http context to increase the size limit.
On /etc/php.ini search the line and set the following directives
;This sets the maximum amount of memory in bytes that a script is allowed to allocate memory_limit = 32M ;The maximum size of an uploaded file. upload_max_filesize = 200M ;Sets max size of post data allowed. This setting also affects file upload. To upload large files, this value must be larger than upload_max_filesize post_max_size = 30M
Restart or reload your php and nginx server.
service nginx restart
service php-fpm restart