When we upgraded our web server a while back to Ubuntu 16.04.1 with PHP7, it broke some applications, our ticket system, Owncloud, a few other minor odds and ends.
I was not able to do an upgrade of ownCloud from version 8 because I did not know that it would not work with PHP7, it only specified minimum version numbers.
Because 9.1 is a fresh install I had to basically wipe everything and start from scratch.
Please do test ownCloud. You can get there two ways:
or https://www.eskimo.com Select Web Apps Pull Down, Click on owncloud.
Please send bug reports to firstname.lastname@example.org.