Upgrade to Debian9 (stretch)

Recently new stable Debian version has been released. Below you will find simple guide for upgrade process.
Be aware, that Debian no longer supports ownCloud. Manual ownCloud upgrade process requires, that you backup all of your data, calendars, contacts etc. before doing so. It’s highly probable that some of it may be lost, and you will need to import it again.

We are starting as usual, from changin packages sources:

# sed -e 's/jessie/stretch/g' -i /etc/apt/sources.list 
# sed -e 's/jessie/stretch/g' -i /etc/apt/sources.list.d/backports.list

Debian9 no longer supports ownCloud, so we are going to keep old package

echo "owncloud hold" | sudo dpkg --set-selections

Upgrade your system

# apt-get update
# apt-get upgrade
# apt-get dist-upgrade
# shutdown -r now

Make sure that apache is still using php5

# a2dismod php7.0

# a2enmod php5

# systemctl restart apache2

Update roundcube database if it failed to do it automatically:

# mysql roundcube < /usr/share/dbconfig-common/data/roundcube/upgrade/mysql/1.2.0-1

Comment “ssl_protocols” in /etc/dovecot/conf.d/10-ssl.conf file