In [3]: from pymongo import MongoClient
   ...:
   ...: client = MongoClient()
   ...: db = client["mydb"]
   ...: [*db.controlUnit.find()]
---------------------------------------------------------------------------
ServerSelectionTimeoutError               Traceback (most recent call last)
Input In [3], in <module>
      3 client = MongoClient()
      4 db = client["hpf-larss-data-access"]
----> 5 [*db.controlUnit.find()]File C:\Anaconda3\lib\site-packages\pymongo\cursor.py:1159, in Cursor.next(self)
   1157 if self.__empty:
   1158     raise StopIteration
-> 1159 if len(self.__data) or self._refresh():
   1160     return self.__data.popleft()
   1161 else:File C:\Anaconda3\lib\site-packages\pymongo\cursor.py:1057, in Cursor._refresh(self)
   1054     return len(self.__data)
   1056 if not self.__session:
-> 1057     self.__session = self.__collection.database.client._ensure_session()
   1059 if self.__id is None:  # Query
   1060     if (self.__min or self.__max) and not self.__hint:File C:\Anaconda3\lib\site-packages\pymongo\mongo_client.py:1603, in MongoClient._ensure_session(self, session)
   1598     return session
   1600 try:
   1601     # Don't make implicit sessions causally consistent. Applications
   1602     # should always opt-in.
-> 1603     return self.__start_session(True, causal_consistency=False)
   1604 except (ConfigurationError, InvalidOperation):
   1605     # Sessions not supported.
   1606     return NoneFile C:\Anaconda3\lib\site-packages\pymongo\mongo_client.py:1553, in MongoClient.__start_session(self, implicit, **kwargs)
   1551 def __start_session(self, implicit, **kwargs):
   1552     # Raises ConfigurationError if sessions are not supported.
-> 1553     server_session = self._get_server_session()
   1554     opts = client_session.SessionOptions(**kwargs)
   1555     return client_session.ClientSession(
   1556         self, server_session, opts, implicit)File C:\Anaconda3\lib\site-packages\pymongo\mongo_client.py:1589, in MongoClient._get_server_session(self)
   1587 def _get_server_session(self):
   1588     """Internal: start or resume a _ServerSession."""
-> 1589     return self._topology.get_server_session()File C:\Anaconda3\lib\site-packages\pymongo\topology.py:530, in Topology.get_server_session(self)
    527 with self._lock:
    528     # Sessions are always supported in load balanced mode.
    529     if not self._settings.load_balanced:
--> 530         session_timeout = self._check_session_support()
    531     else:
    532         # Sessions never time out in load balanced mode.
    533         session_timeout = float('inf')File C:\Anaconda3\lib\site-packages\pymongo\topology.py:514, in Topology._check_session_support(self)
    509         self._select_servers_loop(
    510             any_server_selector,
    511             self._settings.server_selection_timeout,
    512             None)
    513 elif not self._description.readable_servers:
--> 514     self._select_servers_loop(
    515         readable_server_selector,
    516         self._settings.server_selection_timeout,
    517         None)
    519 session_timeout = self._description.logical_session_timeout_minutes
    520 if session_timeout is None:File C:\Anaconda3\lib\site-packages\pymongo\topology.py:216, in Topology._select_servers_loop(self, selector, timeout, address)
    213 while not server_descriptions:
    214     # No suitable servers.
    215     if timeout == 0 or now > end_time:
--> 216         raise ServerSelectionTimeoutError(
    217             "%s, Timeout: %ss, Topology Description: %r" %
    218             (self._error_message(selector), timeout, self.description))
    220     self._ensure_opened()
    221     self._request_check_all()ServerSelectionTimeoutError: mongodb1:27017: [Errno 11001] getaddrinfo failed,mongodb2:27018: [Errno 11001] getaddrinfo failed,mongodb3:27019: [Errno 11001] getaddrinfo failed, Timeout: 30s, Topology Description: <TopologyDescription id: 61f1800055c0a2a6b98c18b6, topology_type: ReplicaSetNoPrimary, servers: [<ServerDescription ('mongodb1', 27017) server_type: Unknown, rtt: None, error=AutoReconnect('mongodb1:27017: [Errno 11001] getaddrinfo failed')>, <ServerDescription ('mongodb2', 27018) server_type: Unknown, rtt: None, error=AutoReconnect('mongodb2:27018: [Errno 11001] getaddrinfo failed')>, <ServerDescription ('mongodb3', 27019) server_type: Unknown, rtt: None, error=AutoReconnect('mongodb3:27019: [Errno 11001] getaddrinfo failed')>]>