Comment 6 for bug 1787284

> Unity migrated forward with 18.04 and should work exactly as it did in 16.04.

Except it did not migrate forward. Certainly not for upgrade from 16.04. Nobody tested upgrade path. We community projects member took it late in 18.04 cycle. As a result Unity (actually compiz) upgrade is broken. Our goal is to keep Unity running for 18.04 and beyond.

You can still use Unity. But you will need a fresh install. Upgrade from 16.04 most likely will not work. You can take backup your documents and restore everything later.