Strongloop启动出现MongoError

错误信息

strongloop@722e85839529:~/lezuzu$ slc run .
INFO strong-agent v1.6.4 profiling app 'lezuzu' pid '27'
INFO strong-agent[27] started profiling agent
INFO supervisor reporting metrics to `internal:`
supervisor running without clustering (unsupervised)
come into Feedback model.
INFO strong-agent not profiling, agent metrics requires a valid license.
Please contact [email protected] for assistance.
Browse your REST API at http://0.0.0.0:3000/explorer
Web server listening at: http://0.0.0.0:3000/
Connection fails:  { [MongoError: connect ECONNREFUSED] name: 'MongoError', message: 'connect ECONNREFUSED' } 
It will be retried for the next request.

/home/strongloop/lezuzu/node_modules/loopback-connector-mongodb/node_modules/mongodb/lib/server.js:228
        process.nextTick(function() { throw err; })
                                            ^
Error: connect ECONNREFUSED
    at errnoException (net.js:905:11)
    at Object.afterConnect [as oncomplete] (net.js:896:19)

root cause or workaround