Errr ‘mongo.js:L112 Error: couldn’t connect to server 127.0.0.1:27017 at src/mongo/shell/mongo.js:L112’

If you are running Ubuntu, then there is an issue with folder ownership.

Run these commands:

1. Stop the MongoDB service

   sudo service mongodb stop
   

2. Remove the MongoDB lock file

   sudo rm /var/lib/mongodb/mongod.lock
   

3. Change ownership from root to the MongoDB path

   sudo chown -R mongodb:mongodb /var/lib/mongodb/
   

4. Start the MongoDB service

   sudo service mongodb start
   

5. Test the mongo application

   mongo
   

Then you will be able to execute successfully (I hope).

Reference: an answer on Stack Exchange site Database Administrators to Error: couldn’t connect to server 127.0.0.1:27017 src/mongo/shell/mongo.js:91 when changing mongodb data directory!