Stop: Unknown instance mongodb (Ubuntu)

I just ran into this.Chances are the issue is in your conf file (obviously, since you reinstalled the seeded)

In the mongodb.conf do not set fork = true if calling it as a service. This will prevent the service call from being able to access it with service mongodb.conf status/stop/restart.

Removing a fork=True line, however, will alleviate the issue.

See comments; use the other solution even though this one is accepted.

The reason you get the Unknown instance error is because upstart is tracking the wrong PID for the instance of forked mongod process. But the proper solution to this is not running the process in foreground by removing fork=true line from the config like @GoingTharn suggesting, but rather helping upstart to capture the right PID of the forked process by adding

expect daemon

to the /etc/init/mongodb.conf

I faced exactly the same problem and did the followings:

• Removed the file mongod.lock (in my case this file was located at /var/lib/mongodb/)
• Used the following command from my mongo client

mongo --repair

And that fixed the issue. It may be noted that I had a system crash prior to this problem appeared. Therefore, what I believe, the problem was caused due to the unclean shutdown of the server demon.

If you are unsure of the reason, you may wish to have a look at the log file (in my case I found it under /var/log/mongodb/). That might give you some useful hints.

Thanks.