i found some issues with the package based installation of zabbix 3.0.11 on Ubuntu 16.04. I had chosen pgsql and webfrontend, like noted in Zabbix 3.0 Documentation. php-bcmath, php-mbstring and php-xml are not in required packages for frontend when installing via apt, this should be changed. Additionally php-pgsql is not in required packages for zabbix-server-pgsql, which causes frontend initialization to fail, because pgsql is not chooseable as database engine.
Additionally database schema does not fit, as frontend initialization fails because of wrong database schema. Fixed it, with dropping database and recreating schema and data with sql scripts from 3.0.11 sources.
Its just a kind of comfort-issue, but misleads, as some of these points aren't documented in official documentation.