I've just installed kvm on my Kubuntu 18.04 and I got a new user listed on my login screen. Apparently, this is an old bug. Some posts here and there suggested that I should create this file:
/var/lib/AccountsService/users/libvirt-qemu
with this content:
[User]
SystemAccount=true
which I did. But it did not fix the issue. The user is still shown on the login screen. One more thing, before I create the file, I had this user listed in my System Settings as an ordinary user. After I created the file, the user is not listed in the User Manager anymore. So the file has done something but all the way through.
Is there anything else I can try?