MongoDB failed to start

  mongodb, question

MongoDB has been unable to start
Always show waiting for connections on port 27017
I have been waiting for a long time!
May I ask what causes this? ..

This is the service already up, waiting for your client to connect, connect tomongodServing … . . . . .

Besides, you can use it to open onecmdUsemongoTry the connection, still waiting. . . . . . . .