So I just tried to install a single domain SSL certificate, I think it succeed but it complains “Something went wrong, sorry.” and then when trying to access admin panel I only got 404 page.
I did some check and seems nginx has lost configuration for /admin, in this file /etc/nginx/conf.d/local.conf
By adding back related configs from https://github.com/mail-in-a-box/mailinabox/blob/master/conf/nginx-primaryonly.conf it works again.
Not sure what goes wrong exactly, tried to check /var/log/syslog but found nothing…