HUGE DISCLAIMER - I am a noob! Like really…
I just decided to move to Nextcould and I want to drop a little bit of knowledge on the moving process.
At this moment I was running latest version of ownCloud 18.104.22.168, following standard update procedure I ended up with this message on the login screen before the update was due to begin “cannot downgrade from 22.214.171.124 to 126.96.36.199”.
So, I opened /var/www/owncloud/config/config.php and changed ‘version’=> ‘188.8.131.52’ to ‘184.108.40.206’.
Saved and reloaded the web page. Update was successful!
I hope this helps a fellow newbie like me.