upgrade dependency error

[Dave Stevens]

 user at user-Satellite-A100 ~ $ sudo apt upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help resolve the situation:

The following packages have unmet dependencies:
 python3-aptdaemon.pkcompat : Conflicts: packagekit but 
1.1.9-1ubuntu2.18.04.6 is to be installed
E: Broken packages

I don't know what the implications of this error are, I'm not using an 
unstable distro as far as I know. Just what I've been using for five 
years.

Arose in the context of a mint version upgrade from 18.3 to 19

TIA

Dave