Could not execute jailcode

I have following error. Please help me to solve this problem.

Staff debug info: Traceback (most recent call last): File "/opt/bitnami/apps/edx/edx-platform/common/lib/xmodule/xmodule/capa_base.py", line 1151, in submit_problem correct_map = self.lcp.grade_answers(answers) File "/opt/bitnami/apps/edx/edx-platform/common/lib/capa/capa/capa_problem.py", line 400, in grade_answers return self._grade_answers(answers) File "/opt/bitnami/apps/edx/edx-platform/common/lib/capa/capa/capa_problem.py", line 462, in _grade_answers results = responder.evaluate_answers(self.student_answers, oldcmap) File "/opt/bitnami/apps/edx/edx-platform/common/lib/capa/capa/responsetypes.py", line 306, in evaluate_answers new_cmap = self.get_score(student_answers) File "/opt/bitnami/apps/edx/edx-platform/common/lib/capa/capa/responsetypes.py", line 3283, in get_score raise ResponseError(msg) ResponseError: Error in evaluating SchematicResponse. The error was: Couldn't execute jailed code: stdout: '', stderr: '/opt/bitnami/apps/edx/venvs/edxapp-sandbox/bin/python: 3: exec: /opt/bitnami/apps/edx/venvs/edxapp-sandbox/bin/.python2.7.bin: Permission denied\n' with status code: 126

Start with the traceback path through capa_base.py, capa_problem.py, and responsetypes.py, then inspect the jailed Python executable at /opt/bitnami/apps/edx/venvs/edxapp-sandbox/bin/.python2.7.bin. Reproduce the SchematicResponse evaluation and investigate the reported permission-denied status 126; done means jailed code executes successfully without this error.