On centos 7, there are instances where you get the error Unable to register authentication agent: GDBus.Error:org.freedesktop.PolicyKit1.Error.Failed: Cannot determine user of subject Error registering authentication agent: GDBus.Error:org.freedesktop.PolicyKit1.Error.Failed: Cannot determine user of subject (polkit-error-quark, 0)

This usually happens when trying to restart a systemd service.

The workaround is as follows:

groupadd … Continue reading How to fix: GDBus.Error:org.freedesktop.PolicyKit1.Error.Failed Centos 7