A problem was encountered and reported via ocflib:

An exception occured in create:

Traceback (most recent call last):
  File "/opt/create/venv/lib/python3.5/site-packages/sqlalchemy/orm/session.py", line 1710, in delete
    state = attributes.instance_state(instance)
AttributeError: 'NoneType' object has no attribute '_sa_instance_state'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/opt/create/venv/lib/python3.5/site-packages/celery/app/trace.py", line 367, in trace_task
    R = retval = fun(*args, **kwargs)
  File "/opt/create/venv/lib/python3.5/site-packages/celery/app/trace.py", line 622, in __protected_call__
    return self.run(*args, **kwargs)
  File "/opt/create/venv/lib/python3.5/site-packages/ocflib/account/submission.py", line 304, in reject_request
    stored_request = get_remove_row_by_user_name(user_name)
  File "/opt/create/venv/lib/python3.5/site-packages/ocflib/account/submission.py", line 292, in get_remove_row_by_user_name
    session.delete(request_row)
  File "/opt/create/venv/lib/python3.5/site-packages/sqlalchemy/orm/session.py", line 1712, in delete
    raise exc.UnmappedInstanceError(instance)
sqlalchemy.orm.exc.UnmappedInstanceError: Class 'builtins.NoneType' is not mapped


Task Details:
  * task_id: 9853248b-ee73-49c2-902c-0199d59033ba

Try `journalctl -u ocf-create` for more details.

====
Hostname: 41424c6fc0e1
Callstack:
    at /opt/create/venv/lib/python3.5/site-packages/ocflib/misc/mail.py:94 (send_problem_report)
        by /opt/create/create/tasks.py:88 (failure_handler)
        by /opt/create/venv/lib/python3.5/site-packages/celery/app/trace.py:205 (handle_failure)
        by /opt/create/venv/lib/python3.5/site-packages/celery/app/trace.py:157 (handle_error_state)
        by /opt/create/venv/lib/python3.5/site-packages/celery/app/trace.py:323 (on_error)
        by /opt/create/venv/lib/python3.5/site-packages/celery/app/trace.py:381 (trace_task)
        by /opt/create/venv/lib/python3.5/site-packages/celery/app/trace.py:530 (_fast_trace_task)
        by /opt/create/venv/lib/python3.5/site-packages/billiard/pool.py:359 (workloop)
        by /opt/create/venv/lib/python3.5/site-packages/billiard/pool.py:290 (__call__)
        by /opt/create/venv/lib/python3.5/site-packages/billiard/process.py:112 (run)
        by /opt/create/venv/lib/python3.5/site-packages/billiard/process.py:306 (_bootstrap)
        by /opt/create/venv/lib/python3.5/site-packages/billiard/popen_fork.py:79 (_launch)
        by /opt/create/venv/lib/python3.5/site-packages/billiard/popen_fork.py:24 (__init__)
        by /opt/create/venv/lib/python3.5/site-packages/billiard/context.py:333 (_Popen)
        by /opt/create/venv/lib/python3.5/site-packages/billiard/process.py:122 (start)
        by /opt/create/venv/lib/python3.5/site-packages/billiard/pool.py:1117 (_create_worker_process)
        by /opt/create/venv/lib/python3.5/site-packages/celery/concurrency/asynpool.py:439 (_create_worker_process)
        by /opt/create/venv/lib/python3.5/site-packages/billiard/pool.py:1008 (__init__)
        by /opt/create/venv/lib/python3.5/site-packages/celery/concurrency/asynpool.py:422 (__init__)
        by /opt/create/venv/lib/python3.5/site-packages/celery/concurrency/prefork.py:112 (on_start)
        by /opt/create/venv/lib/python3.5/site-packages/celery/concurrency/base.py:131 (start)
        by /opt/create/venv/lib/python3.5/site-packages/celery/bootsteps.py:370 (start)
        by /opt/create/venv/lib/python3.5/site-packages/celery/bootsteps.py:119 (start)
        by /opt/create/venv/lib/python3.5/site-packages/celery/worker/worker.py:203 (start)
        by /opt/create/venv/lib/python3.5/site-packages/celery/bin/worker.py:256 (run)
        by /opt/create/venv/lib/python3.5/site-packages/celery/bin/base.py:244 (__call__)
        by /opt/create/venv/lib/python3.5/site-packages/celery/bin/worker.py:221 (run_from_argv)
        by /opt/create/venv/lib/python3.5/site-packages/celery/bin/celery.py:412 (execute)
        by /opt/create/venv/lib/python3.5/site-packages/celery/bin/celery.py:480 (handle_argv)
        by /opt/create/venv/lib/python3.5/site-packages/celery/bin/base.py:281 (execute_from_commandline)
        by /opt/create/venv/lib/python3.5/site-packages/celery/bin/celery.py:488 (execute_from_commandline)
        by /opt/create/venv/lib/python3.5/site-packages/celery/bin/celery.py:326 (main)
        by /opt/create/venv/lib/python3.5/site-packages/celery/__main__.py:14 (main)
        by /opt/create/venv/bin/celery:11 (<module>)