Why does subscription-manager command fail with traceback error "KeyError Unknown feature DBUS_IFACE" ?

Issue

• The command subscription-manager fails with the traceback as follows:

Traceback (most recent call last):
  File "/usr/sbin/subscription-manager", line 67, in <module>
    inj.require(inj.DBUS_IFACE)
  File "/usr/lib64/python2.7/site-packages/subscription_manager/injection.py", line 103, in require
    return FEATURES.require(feature, *args, **kwargs)
  File "/usr/lib64/python2.7/site-packages/subscription_manager/injection.py", line 73, in require
    raise KeyError("Unknown feature: %r" % feature)
KeyError: "Unknown feature: 'DBUS_IFACE'"

• yum is working fine, whereas subscription-manager is not
• yum experiences a package conflict between i686 and x86_64 architectures
• Setting the option multilib_policy=best in yum-config-manager does not fully eradicate the issue