RuntimeError: can't start new thread, база данных pymongo

Полная ошибка:

Exception in thread pymongo_server_monitor_thread:
Traceback (most recent call last):
  File "/app/.heroku/python/lib/python3.9/threading.py", line 973, in _bootstrap_inner
    self.run()
  File "/app/.heroku/python/lib/python3.9/threading.py", line 910, in run
    self._target(*self._args, **self._kwargs)
  File "/app/.heroku/python/lib/python3.9/site-packages/pymongo/periodic_executor.py", line 125, in _run
    if not self._target():
  File "/app/.heroku/python/lib/python3.9/site-packages/pymongo/monitor.py", line 56, in target
    monitor._run()
  File "/app/.heroku/python/lib/python3.9/site-packages/pymongo/monitor.py", line 198, in _run
    self._start_rtt_monitor()
  File "/app/.heroku/python/lib/python3.9/site-packages/pymongo/monitor.py", line 156, in _start_rtt_monitor
    self._rtt_monitor.open()
  File "/app/.heroku/python/lib/python3.9/site-packages/pymongo/monitor.py", line 84, in open
    self._executor.open()
  File "/app/.heroku/python/lib/python3.9/site-packages/pymongo/periodic_executor.py", line 87, in open
    thread.start()
  File "/app/.heroku/python/lib/python3.9/threading.py", line 892, in start
    _start_new_thread(self._bootstrap, ())
RuntimeError: can't start new thread
Traceback (most recent call last):
  File "/app/.heroku/python/lib/python3.9/site-packages/discord/ext/commands/bot.py", line 606, in _load_from_module_spec
    spec.loader.exec_module(lib)
  File "<frozen importlib._bootstrap_external>", line 850, in exec_module
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "/app/cogs/hug.py", line 9, in <module>
    cluster = pymongo.MongoClient(mongo_key)
  File "/app/.heroku/python/lib/python3.9/site-packages/pymongo/mongo_client.py", line 750, in __init__
    self._get_topology()
  File "/app/.heroku/python/lib/python3.9/site-packages/pymongo/mongo_client.py", line 1238, in _get_topology
    self._topology.open()
  File "/app/.heroku/python/lib/python3.9/site-packages/pymongo/topology.py", line 172, in open
    self._ensure_opened()
  File "/app/.heroku/python/lib/python3.9/site-packages/pymongo/topology.py", line 539, in _ensure_opened
    self._update_servers()
  File "/app/.heroku/python/lib/python3.9/site-packages/pymongo/topology.py", line 662, in _update_servers
    server.open()
  File "/app/.heroku/python/lib/python3.9/site-packages/pymongo/server.py", line 49, in open
    self._monitor.open()
  File "/app/.heroku/python/lib/python3.9/site-packages/pymongo/monitor.py", line 84, in open
    self._executor.open()
  File "/app/.heroku/python/lib/python3.9/site-packages/pymongo/periodic_executor.py", line 87, in open
    thread.start()
  File "/app/.heroku/python/lib/python3.9/threading.py", line 892, in start
    _start_new_thread(self._bootstrap, ())
RuntimeError: can't start new thread