I am a windows user and I installed MongoDB in November 2018 and I didn't wanted to setup data/db directories. But after few days, when I open, got an error message:

MongoDB shell version v4.0.4
connecting to: mongodb://127.0.0.1:27017
2018-12-05T20:42:40.108+0530 E QUERY    [js] Error: couldn't connect to server 127.0.0.1:27017, connection attempt