I 2 days back tried to update the OwnCloud 7.x on my pi to 8.x when I saw the message on the owncloud interface. I tried the updater tool and it failed. So I ran
sudo apt-get install owncloud and it downloaded the owncloud tar and placed it properly. I followed the instructions here: https://doc.owncloud.org/server/8.0/admin_manual/maintenance/upgrade.html
Why I said 'properly' is that when I opened owncloud using my browser, I saw that the owncloud installation was ready for update. I clicked on update and it ran forever.
Now the service is stopped and I cannot connect to owncloud.
Any pointer for help?