Ojs hosted on ubuntu cloud server throws 503 service unavailable error

I am using ojs 3.1.1 but when I hosted on google cloud. It throws an error when I tried to log in. The error shows service unavailable 503. Anyone encounter such error and what’s the solution? Thanks urgent

Hi @haixun,

Check your server’s error log for details.

Alec Smecher
Public Knowledge Project Team

I am using apache2 server and checked the error log there is nothing unusual shown. It happens when I attempt to login. There throws a service unavailable 503 error. Sometimes I am able to login but shown with ## api.unknownError ##How do u toggle php log?