sqlalchemy.exc.InvalidRequestError: This session is in 'prepared' state; no further SQL can be emitted within this transaction

Suddenly appeared after a 5min stream and 5min file timeslot was scheduled. Playback was not interfered.

2021-07-13 16:20:01,606:AuraEngine:INFO - Expanded duration of playlist entry #0 - [programme.py:512-expand_entry_duration()]
2021-07-13 16:20:01,611:AuraEngine:INFO - Finished with fading-in 'in_filesystem_1'. - [mixer.py:369-fade_in()]
Exception in thread PLAY:do_play:1626186000.0:
Traceback (most recent call last):
  File "/usr/lib/python3.8/threading.py", line 932, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.8/threading.py", line 1254, in run
    self.function(*self.args, **self.kwargs)
  File "/home/david/Code/aura/engine/src/control.py", line 294, in wrapper_func
    if param: self.func(param,)
  File "/home/david/Code/aura/engine/src/scheduling/scheduler.py", line 517, in do_play
    self.logger.info(self.engine.scheduler.timeslot_renderer.get_ascii_timeslots())
  File "/home/david/Code/aura/engine/src/scheduling/utils.py", line 236, in get_ascii_timeslots
    entries = self.preprocess_entries(rest_of_playlist, False)
  File "/home/david/Code/aura/engine/src/scheduling/utils.py", line 322, in preprocess_entries
    if entry.entry_start >= entry.playlist.timeslot.timeslot_end:
  File "/home/david/Code/aura/engine/python/lib/python3.8/site-packages/sqlalchemy/orm/attributes.py", line 287, in __get__
    return self.impl.get(instance_state(instance), dict_)
  File "/home/david/Code/aura/engine/python/lib/python3.8/site-packages/sqlalchemy/orm/attributes.py", line 723, in get
    value = self.callable_(state, passive)
  File "/home/david/Code/aura/engine/python/lib/python3.8/site-packages/sqlalchemy/orm/strategies.py", line 749, in _load_for_state
    return self._emit_lazyload(
  File "<string>", line 1, in <lambda>
  File "/home/david/Code/aura/engine/python/lib/python3.8/site-packages/sqlalchemy/orm/strategies.py", line 890, in _emit_lazyload
    q(session)
  File "/home/david/Code/aura/engine/python/lib/python3.8/site-packages/sqlalchemy/ext/baked.py", line 545, in all
    return list(self)
  File "/home/david/Code/aura/engine/python/lib/python3.8/site-packages/sqlalchemy/ext/baked.py", line 445, in __iter__
    return q._execute_and_instances(context)
  File "/home/david/Code/aura/engine/python/lib/python3.8/site-packages/sqlalchemy/orm/query.py", line 3502, in _execute_and_instances
    conn = self._get_bind_args(
  File "/home/david/Code/aura/engine/python/lib/python3.8/site-packages/sqlalchemy/orm/query.py", line 3517, in _get_bind_args
    return fn(
  File "/home/david/Code/aura/engine/python/lib/python3.8/site-packages/sqlalchemy/orm/query.py", line 3496, in _connection_from_session
    conn = self.session.connection(**kw)
  File "/home/david/Code/aura/engine/python/lib/python3.8/site-packages/sqlalchemy/orm/session.py", line 1138, in connection
    return self._connection_for_bind(
  File "/home/david/Code/aura/engine/python/lib/python3.8/site-packages/sqlalchemy/orm/session.py", line 1146, in _connection_for_bind
    return self.transaction._connection_for_bind(
  File "/home/david/Code/aura/engine/python/lib/python3.8/site-packages/sqlalchemy/orm/session.py", line 409, in _connection_for_bind
    self._assert_active()
  File "/home/david/Code/aura/engine/python/lib/python3.8/site-packages/sqlalchemy/orm/session.py", line 282, in _assert_active
    raise sa_exc.InvalidRequestError(
sqlalchemy.exc.InvalidRequestError: This session is in 'prepared' state; no further SQL can be emitted within this transaction.
2021-07-13 16:20:01,647:AuraEngine:INFO - Expanded duration of playlist entry #0 - [programme.py:512-expand_entry_duration()]
2021-07-13 16:20:01,674:AuraEngine:INFO - Finished fetching current programme from API (3 timeslots) - [programme.py:80-refresh()]