A few month ago I installed OwnCloud on my Ubuntu 14.04 server with the ppa.
Today I updated my server with apt dist-upgrade and a new server version was installed.
After that I could not access until I disabled maintenance mode manually:
sudo -u www-data php occ maintenance:mode --off
Now I get the message:
Exception: Updates between multiple major versions and downgrades are unsupported.
There is a link for this problem, telling my to install first a skipped mayor update. But I am not sure which version I have.
Steps to reproduce
Install old version of OwnCloud and update it with you system (ppa)
Should work or show version of old installation