OS: Debian 8 , Apache 2.4 Upgrading from : 126.96.36.199p9 Upgrading to : 3.1.6 After upgrading I'm not able to log in to the control panel. In /var/log/ispconfig/auth.log I'm getting Successful login for user 'admin' from xx.xx.xx.xx at 2017-09-01 12:21:01 but the page just reloads to display login window again Have previously upgraded from :188.8.131.52p9 to 3.1.5 and everything was fine This time tried downloading older versions and downgraded, but only after downgrading to 184.108.40.206p9 I was able to log in to the control panel again. ( downgraded by downloading previous versions, un-tar'ing and running Code: /usr/src/ispconfig3_install/install# php -q update.php Any thoughts how can this version be upgraded ? Strangely enough I made a copy of this VM previously, removed all sites and it did upgrade successfully to 3.1.5 a few months ago. It was the latest stable back then.