[SOLVED] Distribution upgrade Stretch to Buster fails

[Nachteule]

You have apache2 and dnsmasq installed

Code:

insserv: FATAL: service dnsmasq is missed in the runlevels 2 3 4 5 to use service apache2

That's causing the error.

Could you try

A) set package dnsmasq and apache2 on hold before running upgrade
sudo apt-mark hold apache2 && sudo apt-mark hold dnsmasq and try again

or

B) temporarly deinstall both packages, run the upgrade and reinstall them after upgrade has been done