Hi @mediasync,
All the DB1_.* ENV vars and other important vars the postinst scripts use are defined in /etc/kaltura.d/system.ini which is a symlink to /opt/kaltura/app/configurations/system.ini.
Is it possible you deleted it by mistake?
It would surely exist now since you’ve reconfigured the kaltura-base package successfully [which triggers the exec of /var/lib/dpkg/info/kaltura-base.postinst] but if it didn’t exist when you tried to upgrade the reason for failure is obvious.