[APIGEE] API requests made to apigee server throws exception "scripts.node.runtime.ScriptStillStart

[psvnlsaikumar]

1. The error rate was very high last month. Until there is a restart to the servers, the issue remains.
2. No change was made to the server except for restart, and we have stopped restarting recently, and we are not encountering issue. 
3. This is an intermittent issue which keeps showing up.
4. The nodejs engine that is running is trireme

Any help which would point to this issue would be appreciated. We have added a lot of loggers, and are not able to find the root cause.

error trace :- 

pathtoRegexp (/organization/environment/api/node_modules/path-to-regexp/index.js:101:0),     at Layer (/organization/environment/api/node_modules/express/lib/router/layer.js:45:0),     at use (/organization/environment/api/node_modules/ 
express/lib/router/index.js:464:0),     at /organization/environment/api/node_modules/express/lib/application.js:220:0,     at use (/organization/environment/api/node_modules/express/lib/application.js:217:0),     at /organization/environment/api/app.js:100:0,     at module.js:456:0,     at module.js:474:0,     at module.js:356:0,     at module.js:312:0,     at module.js:497:0,     at startup (trireme.js:142:0),     at trireme.js:923:0, ]

////// 

API response  :- 

<faultstring>Script node is still starting</faultstring><detail><errorcode>scripts.node.runtime.ScriptStillStarting</errorcode></detail></fault>