mongo.conf is wrong.
file has lines mixed up.
[mongo.conf] # engine: # mmapv1: # wiredTiger: # how the process runs processManagement: fork: true # fork and run in background pidFilePath: /var/run/mongodb/mongod.pid # location of pidfile # network interfaces net: port: 27017 bindIp: 127.0.0.1 # Listen to local interface only, comment to listen on all interfaces. #security: #operationProfiling: