Why is PyMongo 3 giving ServerSelectionTimeoutError?

Question

I\'m using:

• Python 3.4.2
• PyMongo 3.0.2
• mongolab running mongod 2.6.9
• uWSGI 2.0.10
• CherryPy 3.7.0
• nginx 1.6.2

Answer 1

In my case

• I was using Mongo Atlas
• I got another IP adress after a router reboot

hence I had to add that IP to the whitelist on Mongo Atlas settings via

MongoAtlas website -> Network Access -> IP Whitelist -> Add IP Address -> Add Current IP Address

then wait for IP Address's status to change to Active and then try to run the app again

Answer 2

I had the same problem with Pymongo 3.5 Turns out replacing localhost with 127.0.0.1 or corresponding ip address of your mongodb instance solves the problem.

Answer 3

I'm using pymongo 3.2 and I run into the same error, however it was a missconfiguration in my case. After enabling authorization, I forgot to update the port in the url which ended up in a connection timout. Probably it is worth to mention that ?authSource might be required as it is typically different than the database storing the application data.

Answer 4

That error has occurred because there is no MongoDB server running in the background. To run the MongoDB server open cmd or anaconda prompt and type this:-

"C:\Program Files\MongoDB\Server\3.6\bin\mongod.exe"

then run

import pymongo
myclient = pymongo.MongoClient()    
mydb = myclient["mydatabase"]
myclient.list_database_names()

Answer 5

I solved this by installing dnspython (pip install dnspython). The issue is that: "The "dnspython" module must be installed to use mongodb+srv:// URIs"

Answer 6

pymongo 3 will not tell you your connection failed when you instantiate your client. You may not be connected.

https://api.mongodb.com/python/3.5.1/api/pymongo/mongo_client.html

"it no longer raises ConnectionFailure if they are unavailable .. You can check if the server is available like this:"

from pymongo.errors import ConnectionFailure
client = MongoClient()
try:
    # The ismaster command is cheap and does not 
require auth.
    client.admin.command('ismaster')
except ConnectionFailure:
    print("Server not available")