Keep on getting the following warning on my node.js server

Question

My console keeps on giving the following warnings. This could be from app.js or from any of the other route files:

The error seems to be coming because of my cache handling. I handle cache once the user logs out.

Error: Can't set headers after they are sent.
    at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:344:11)
    at ServerResponse.header (/home/ved/Dropbox/JAVA/eBay/test/node_modules/express/lib/response.js:718:10)
    at ServerResponse.send (/home/ved/Dropbox/JAVA/eBay/test/node_modules/express/lib/response.js:163:12)
    at done (/home/ved/Dropbox/JAVA/eBay/test/node_modules/express/lib/response.js:957:10)
    at View.exports.renderFile [as engine] (/home/ved/Dropbox/JAVA/eBay/test/node_modules/ejs/lib/ejs.js:363:10)
    at View.render (/home/ved/Dropbox/JAVA/eBay/test/node_modules/express/lib/view.js:126:8)
    at tryRender (/home/ved/Dropbox/JAVA/eBay/test/node_modules/express/lib/application.js:639:10)
    at EventEmitter.render (/home/ved/Dropbox/JAVA/eBay/test/node_modules/express/lib/application.js:591:3)
    at ServerResponse.render (/home/ved/Dropbox/JAVA/eBay/test/node_modules/express/lib/response.js:961:7)
    at /home/ved/Dropbox/JAVA/eBay/test/app.js:159:7
GET /fonts/glyphicons-halflings-regular.woff 404 1.673 ms - 968
GET /fonts/glyphicons-halflings-regular.ttf 404 1.738 ms - 968
POST /viewProductPage - - ms - -

app.js

var express      = require('express');
var path         = require('path');
var favicon      = require('serve-favicon');
var logger       = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser   = require('body-parser');


//DEFINING EXTERNAL DEPENDENCY TO ENABLE SESSIONS IN THE APPLICATION
var session = require('client-sessions');


//DEFINING THE BASE ROUTE
var routes = require('./routes/index');

//DEFINING THE ROUTE TO GET THE SYSTEM USERS
var users  = require('./routes/users');


//DEFINING THE ROUTE TO ACCESS sell.js
//sell.js HANDLES ALL THE ITEMS POSTED
//INTERACTS WITH THE DATABASE FOR THE SAME
var sell = require('./routes/sell');


//ROUTES TO getUserData.js
//DEFINED AS A BASE ROUTE TO ACCESS SESSION FOR ANY USE
var getUserData = require('./routes/getUserData');





var productsRetriever = require('./routes/productsRetriever');


//DEFINING THE DEPENDENCY TO ACCESS LOGIN CONTROLS FOR THE SYSTEM
//USER LOGIN AND MOST IMPORTANTLY ASSIGNING A SESSION TO THAT USER IS HANDLED BY login.js
//getUserData.js RETRIEVES THE SESSION OF A USER INITIATED IN login.js
var login    = require('./routes/login');





var productDetail    = require('./routes/productDetail');



//DEFINING THE DEPENDENCY TO ACCESS register.js
//register.js HANDLES ALL THE USER REGISTRATION PATHS AS WELL AS FUNCTIONS
var register = require('./routes/register');



//INITIATING AN INSTANCE OF express js IN OUR APPLICATION
//ASSIGNING IT TO A VARIABLE APP
var app      = express();



// all environments
//configure the sessions with our application
app.use(session({
    cookieName    : 'session',
    secret        : 'cmpe273_ebay_app_fall_2016',
    duration      : 30 * 60 * 1000, //setting the time for active session
    activeDuration: 5 * 60 * 1000 // setting time for the session to be active when the window is open // 5 minutes set currently
})); 





// view engine setup
//SETS BASE PATH FOR ALL THE FILES IN THE VIEW
app.set('views', path.join(__dirname, 'views'));
//ASSIGNING THE ejs ENGINE TO ALL THE FILES WITHIN VIEWS DIRECTORY
app.set('view engine', 'ejs');

// uncomment after placing your favicon in /public
app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));


//GETS THE PATH WHEN A USER FIRST VISITS OUR APPLICATION
app.get('/', routes);


app.get('/users', users);

app.get('/login', login.login);
app.post('/checklogin', login.checklogin);
app.get('/getAllUsers', login.getAllUsers);


app.get('/sell', sell.sell);
app.post('/addSellItem', sell.addSellItem);


//app.post('/checklogin', login.checklogin);
app.get('/homepage',login.redirectToHomepage);





app.post('/logout',login.logout);



app.post('/getUserInfo', getUserData.getUserData);

app.get('/viewProduct',productDetail.getProductPage);

app.post('/productsRetriever', productsRetriever.getProducts);


app.post('/viewProductPage', productDetail.getProductPageDetails);

app.get('/register', register.register);
app.post('/registerdone', register.registerdone);
app.get('/getAllRegisteredUsers', register.getAllRegisteredUsers);





// catch 404 and forward to error handler
app.use(function(req, res, next) {
  var err                               = new Error('Not Found');
  err.status                            = 404;
  next(err);
});

// error handlers

// development error handler
// will print stacktrace
if (app.get('env')                      === 'development') {
  app.use(function(err, req, res, next) {
    res.status(err.status || 500);
    res.render('error', {
      message                           : err.message,
      error                             : err
    });
  });
}


// production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
  res.status(err.status || 500);
  res.render('error', {
    message                             : err.message,
    error                               : {}
  });
});


module.exports                          = app;

How does this question is differ from this one http://stackoverflow.com/q/7042340/744534 — Thaadikkaaran, Oct 13 '16 at 08:50
In which call are you getting this error?can you post that code? — abdulbarik, Oct 13 '16 at 08:53
Are you doing any job to request any route on particular time, since this error shows that you are sending more than one response — abdulbarik, Oct 13 '16 at 09:15
Seems to happen in `productDetail.getProductPageDetails`, judging by the log. — robertklep, Oct 13 '16 at 11:49

score 0 · Answer 1 · answered Oct 13 '16 at 12:33

This has happened to me also.

What the issue was (for me) was that I was doing some operations in my routes and was sending response to user but after that error occured and it was handled by the error handling middleware (bottom part of your app.js) and it was sending the error response.

But as the request was already responded to earlier in your API route, this error message comes in the logs. Try finding what the error is.

Try putting console.log() in your error handlers to see the trace.

Keep on getting the following warning on my node.js server

1 Answers1