dbus: [system] Failed to activate service 'org.freedesktop.login1': timed out

Restart logind:

# systemctl restart systemd-logind

Beware that restarting dbus will break their connection again.

Reboot was the only solution that worked for me. I killed the runaway dbus process and other things failed.

This is what happened when i tried to reload httpd-

Error getting authority: Error initializing authority: Error calling StartServiceByName for org.freedesktop.PolicyKit1: GDBus.Error:org.freedesktop.DBus.Error.TimedOut: Activation of org.freedesktop.PolicyKit1 timed out (g-dbus-error-quark, 20)
Failed to reload httpd.service: Connection timed out

Centos7 is buggy.

Restarting only systemd-logind service is not enough, it just postpones the main problem.

Seems like this is caused by too many files pilled up under '/run/systemd/system/', created by the service and not properly cleaned up, especially on hosts with a lot of logins. Eventually after some time you would start seeing some weird behavior like hostnamectl not reporting a thing, or timedatectl reports Failed to query server: Connection timed out and other odd things. As well the symptoms reported originally.

One workaround is to delete all 'session-*.scope' files and to restart systemd. Restarting the host is not necessary in that case. This probably is related to a bug in systemd and dbus, hopefully in next updates they will be fixed.