pm2启动项目报错

Question

项目用node app.js启动没有任何问题，换成pm2 start app.js以后，页面刷新有时会出现502，而且websocket连接不上，日志报下面的错。

 Error: spawn ELOOP
0|app      |     at exports._errnoException (util.js:1050:11)
0|app      |     at ChildProcess.spawn (internal/child_process.js:319:11)
0|app      |     at exports.spawn (child_process.js:378:9)
0|app      |     at Object.exports.execFile (child_process.js:143:15)
0|app      |     at Object.Dependencies.collect (/usr/lib/node_modules/pm2/node_modules/_pmx@1.5.5@pmx/lib/dependencies.js:9:16)
0|app      |     at Timeout._onTimeout (/usr/lib/node_modules/pm2/node_modules/_pmx@1.5.5@pmx/lib/pmx.js:78:18)
0|app      |     at ontimeout (timers.js:386:14)
0|app      |     at Timer.unrefdHandle (timers.js:492:5

求解