Comment 1 for bug 1726504

"as it had before the upgrade" -> do you per chance have upgrade logs? e.g. /var/log/apt/* files?
To check if /etc/systemd/logind.conf conffile was overwritten. Local modifications should be preserved on upgrades and apt logs should mention if logind.conf was rewritten or not.

The defaults have not changed in artful. RemoveIPC in logind.conf has been yes since introduction in v211, which is pre-xenial.

There has been no changes to the defaults, so further investigation / logs are required from the affected system.