Warning: session_write_close(): Session callback expects true/false return value in Unknown on line 0
Warning: session_write_close(): Failed to write session data using user defined save handler. (session.save_path: /var/lib/php/sessions) in Unknown on line 0
This in current dev environment:
$ php -v
PHP 7.1.3-3+deb.sury.org~xenial+1 (cli) (built: Mar 25 2017 14:00:03) ( NTS )
Copyright (c) 1997-2017 The PHP Group
Zend Engine v3.1.0, Copyright (c) 1998-2017 Zend Technologies
with Zend OPcache v7.1.3-3+deb.sury.org~xenial+1, Copyright (c) 1999-2017, by Zend Technologies
$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.04
DISTRIB_CODENAME=xenial
DISTRIB_DESCRIPTION="Ubuntu 16.04.2 LTS"
This in current dev environment:
Cause unknown, obviously related to sessions.