Server slection timeout error how to solve

ServerSelectionTimeoutError pymongo.errors.ServerSelectionTimeoutError: 127.0.0.1:27017: [Errno 111] Connection refused, Timeout: 30s, Topology Description: <TopologyDescription id: 6533a7fa644f86b3222a4e79, topology_type: Unknown, servers: [<ServerDescr

Is mongod running?

Can you connect with Compass or mongosh?

The error

often means that no process is listening on the given IP and port?

What is your OS?

Hello Guys,
please solve the below error
server selection time out error .my os is Ubuntu ,i removed the Mongodb and again install but still occur this error after the system update .I’m used 3T studio for data showing as GUI format ,i provide the details about the error please provide the solution

ServerSelectionTimeoutError

pymongo.errors.ServerSelectionTimeoutError: 127.0.0.1:27017: [Errno 111] Connection refused, Timeout: 30s, Topology Description: <TopologyDescription id: 65a62b9cf902c9322efcc3ca, topology_type: Unknown, servers: [<ServerDescription (‘127.0.0.1’, 27017) server_type: Unknown, rtt: None, error=AutoReconnect(‘127.0.0.1:27017: [Errno 111] Connection refused’)>]>

and in terminal show the below error
MongoNetworkError: connect ECONNREFUSED 127.0.0.1:27017
or Core Dumped also show

Like already mentioned

Please ensure that mongod is running and listening on 127.0.0.1 on port 27017. To do that you use the commands:

ps -aef | grep [m]ongod
ss -tlnp