NameError when tried preview certificate from studio

[sai venkata vinay pasupuleti]

Hi Guys,

I am getting the following error. When clicked on 'Preview Certificate' in Studio.

Please, Let me if you know any solution.

ERROR:

NameError at /certificates/user/5/course/course-v1:Python.org+CS102+2018_T1

Undefined

Request Method:	GET
Request URL:	http://localhost:8000/certificates/user/5/course/course-v1:Python.org+CS102+2018_T1?preview=professional
Django Version:	1.8.18
Exception Type:	NameError
Exception Value:	Undefined
Exception Location:	/edx/app/edxapp/venvs/edxapp/local/lib/python2.7/site-packages/mako/runtime.py in __str__, line 226
Python Executable:	/edx/app/edxapp/venvs/edxapp/bin/python
Python Version:	2.7.12
Python Path:	['.', '.', '/edx/app/edxapp/edx-platform', '/edx/app/edxapp/venvs/edxapp/lib/python2.7', '/edx/app/edxapp/venvs/edxapp/lib/python2.7/plat-x86_64-linux-gnu', '/edx/app/edxapp/venvs/edxapp/lib/python2.7/lib-tk', '/edx/app/edxapp/venvs/edxapp/lib/python2.7/lib-old', '/edx/app/edxapp/venvs/edxapp/lib/python2.7/lib-dynload', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-x86_64-linux-gnu', '/usr/lib/python2.7/lib-tk', '/edx/app/edxapp/venvs/edxapp/local/lib/python2.7/site-packages', '/edx/app/edxapp/venvs/edxapp/src/code-block-timer', '/edx/app/edxapp/venvs/edxapp/src/pystache-custom', '/edx/app/edxapp/venvs/edxapp/src/pygeoip', '/edx/app/edxapp/venvs/edxapp/src/edx-jsme', '/edx/app/edxapp/venvs/edxapp/src/parse-rest', '/edx/app/edxapp/venvs/edxapp/src/codejail', '/edx/app/edxapp/venvs/edxapp/src/event-tracking', '/edx/app/edxapp/venvs/edxapp/src/django-splash', '/edx/app/edxapp/venvs/edxapp/src/acid-xblock', '/edx/app/edxapp/venvs/edxapp/src/edx-submissions', '/edx/app/edxapp/venvs/edxapp/src/rate-xblock', '/edx/app/edxapp/venvs/edxapp/src/done-xblock', '/edx/app/edxapp/venvs/edxapp/src/xblock-google-drive', '/edx/app/edxapp/edx-platform', '/edx/app/edxapp/edx-platform/common/lib/calc', '/edx/app/edxapp/edx-platform/common/lib/capa', '/edx/app/edxapp/edx-platform/common/lib/chem', '/edx/app/edxapp/edx-platform/common/lib/dogstats', '/edx/app/edxapp/edx-platform/common/lib/safe_lxml', '/edx/app/edxapp/edx-platform/common/lib/sandbox-packages', '/edx/app/edxapp/edx-platform/common/lib/symmath', '/edx/app/edxapp/edx-platform/common/lib/xmodule', '/edx/app/edxapp/edx-platform/openedx/core/lib/xblock_builtin/xblock_discussion', '/edx/app/edxapp/venvs/edxapp/lib/python2.7/site-packages', '/edx/app/edxapp/edx-platform', Path(u'/edx/app/edxapp/edx-platform'), Path(u'/edx/app/edxapp/edx-platform/lms/djangoapps'), Path(u'/edx/app/edxapp/edx-platform/common/djangoapps')]
Server time:	Wed, 11 Apr 2018 01:25:20 -0400

Thanks.