Nextcloud blank after login in

I have problem, i registered account in nextcloud setup(i mean in web interface), after i logged in it gives me blank page
Running it OS ubuntu 18.04
php 7.3
I added my external ip and domain to trusted domain, but it’s still blank.
I looked at php log, it said that cannot connect to database, but wordpress is working and 3306 port is forwarded
(Nextcloud is subwebsite)

Here’s screen of apache2 error.log