Thanks Hongbin,
This Issue has been resolved.

On Sat, 22 Aug 2020, 23:41 Hongbin Lu, <hongbin034@gmail.com> wrote:
How did you install python-zunclient? and how did you install openstackclient? My best guess is the mess up of python2/3 environment. Mind pasting output of the following commands?

$ pip --version
$ pip freeze
$ pip3 freeze

On Sat, Aug 22, 2020 at 3:03 PM mahdi abbasi <mahdi.abbasi.2013@gmail.com> wrote:
Hi openstack development team,

I installed python-zunclient successfully but openstack appcontainer command steal return not found. Please help me.

Best regards
Mahdi