Wordpress multisite is down after upgrade Ubuntu to 16.04
So I was using an One-click-Wordpress on Ubuntu 14.04 from 2015. I converted it to multisite in 2016 and still running fine with 5 sites total (with different domains).
Problems came yesterday when I decied to do an do-release-upgrade to upgrade to Ubuntu 16.04. Without any active droplet snapshot. Yes, that was awful.
After the upgrade, my sites are still down. I sent a DigitalOcean support ticket to get me through some droplet check. Then I checked apache2 service and it was not running caused by syntax errror 'php_flag'. And so I reinstalled php and check some other LAMP stack related stuffs.
After a while, my sub-sites are back online, as I can access them via their own domain. But I cannot access my main site, the original domain. And so I cant backup things from there.
These are the symptoms:
- Access my-main-domain (through cloudflare) get only a blank page with code 500 error.
- Access my-droplet-ip and I got redirect to http://my-main-domain/wp-signup.php?new=my-droplet-ip
- My sub-sites still running.
I thinks this is is some multisites config got messed up after the upgrade but do not know how to solve the problem. So I appreciate any help from the community, thank you very much.