Owncloud 8.2.1 Can't login thru Web Interface - no error message

Server
1

Operating system: centos 7
Web server: nginx
Database: Mariadb
PHP version: 7.0
ownCloud version 8.2.1
Updated from an older ownCloud or fresh install: fresh

fix

2

ownCloud 8.2.1 is outdated and incompatible to PHP7