MongoDB error: child process failed, exited with error number

MongoDB eror "child process failed, exited with error number 1, 14, 48, ..." 

Check all path in /etc/mongod.conf. If files or folders not exist, create them then:

sudo chown -R mongod:mongod <path in that file>
# maybe your user is mongodb, or mongod
fuser -k 27017/tcp

sudo mongod --fork --config /etc/mongod.conf --logpath /var/log/mongodb/mongod.log