To anyone who have fresh install of wordpress + nginx, remember to disable the mysql log if you do not have master/slave database. Otherwise, it will be a TIME BOMB and you will be seeing 502 bad gateway on your website soon. I have two website using literally different plugin have same problem. Anyway I am still gladful to have bitnami for my wordpress site.
Solution you need:
sudo rm /opt/bitnami/mysql/data/binlog.0*
sudo nano /opt/bitnami/mysql/my.cnf
/opt/bitnami/ctlscript.sh start mysql