All of my wordpress websites on cyberpanel suddenly shows error 503

All of my wordpress websites on cyberpanel suddenly shows error 503, Can anyone please help me.

Welcome @vishaljethwani Happy you are here

1. Are you using modsecurity ? Disable it and try again

2. Probably you reached max children process limit. You can confirm this by checking /usr/local/lsws/logs/lsrestart.log to fix this just restart lsws service

$ systemctl restart lsws || service lsws reload

This means you might be having so many php processes running you will need to run High CPU Usage, 4CPU 8GB RAM - #19 by josephgodwinke

Makes sure to run upgrade script and reboot your server