Why errata's not getting listed in the Red Hat Satellite v6 for system profile? and Why katello-package-upload command fails with "ImportError: cannot import name certmgr" error?

Issue

• Errata's are not getting listed in the Red Hat Satellite v6 webui, after installing katello-agent package on the client systems.
• Getting traceback errors on running katello-package-upload command.

[root@localhost ~]# katello-package-upload
Traceback (most recent call last):
  File "/usr/sbin/katello-package-upload", line 19, in <module>
    import package_upload
  File "/usr/lib/yum-plugins/package_upload.py", line 19, in <module>
    from subscription_manager import certmgr
ImportError: cannot import name certmgr