Meteor: Unexpected mongo exit code 100. Restarting.Can’t start mongo server

The folowing steps that solved instance of this problem,

1. Delete .meteor/local/db/mongod.lock
2. Delete .meteor/local/db/journal/j.*
3. sudo meteor

sudo might not be necessary but it was the only way back into the app for me. Hope that saves someone a bit of time getting back up and running.