I recently just had to sink 3 days of my own into navigating a way from Ubuntu 14.04 and OC 8.0.2 (!) to something current. It was a real S#!tshow… but I can try to share how I went about it. I was personally able to snapshot my VPS and separate ‘owncloud data’ block storage device separately… so I could try different approaches to … inch… myself forward, and just revert back if things exploded on me. I also tried to take notes as complete as possible when doing so. They are terse, but hopefully they are of some help:
First focused on doing manual OC version upgrades to last 8.X release:
“successfully upgraded from OC 8.0.2 to 8.1.12, then to 8.2.11… Services are still left in maintenance mode”
At this point, I noticed that OC 8.2.11 was fixing a whole slew of bad file CACHE entries on my instance. my OwnCloud “data” volume is exceedingly slow, so this literally took HOURS to fix itself and work through the issues
Still at Ubuntu 14.04 and PHP 5, I cautiously upgraded to OC 9.0.11
This was successful, and I monitored for awhile, bringing services out of maintenance mode (To let family and friends have their clients sync… and tailing the owncloud log for indications that something had gone sideways). Everything appeared healthy… so I proceeded with my next big step;
Back to maintenance mode, I attempted to upgrade from PHP 5.X to PHP7
This was the most labour intensive part of my particular ordeal. My notes may not be 100%.
service apache2 stop
After adding the repository sources for PHP7 on my Ubuntu 14.04 instance… I installed the following packages:
I then purged the old PHP5:
apt-get purge php5-common
I also have a note about modifying a php.ini file to allow for ‘short tags’ (may or may not have been required):
something about short tags???”
I then enabled PHP7 in Apache with:
… and restarted the Apache webserver:
service apache2 restart
At this point, I again took things out of Maintenance mode and appeared to have a fully functional OC 188.8.131.52 installation on PHP7 and Ubuntu 14.04
I then did a do-release-upgrade to 16.04 LTS, which succeeded without issue
Finally, I did another manual OC upgrade to version 10.0.10… which was successful
I now sit on 16.04 LTS w/ PHP 7.0 and OC 10.0.10. Eventually, the friends and family (and all their mobile apps) all sync’d to the server and all was right with the world again.
I hope some part of my own ordeal is of use to you.