Comment 33 for bug 996916

I'm surprised: 8 years later, the bug is still here.

I wanted to upgrade from 18.04 to 20.04 and faced the exact same issue caused by postgis.

What worked for me were to remove postgis, do the upgrade, and re-install postgis:

sudo apt remove postgresql-12-postgis-*

sudo do-release-upgrade

sudo apt install postgresql-12-postgis-3