ERR_HTTP_HEADERS_SENT: Cannot set headers after they are sent to the client

Question

I\'m facing this weird issue in NodeJS when using with Passport.js, Express and Mongoose. Basically, I get an error saying \"Cannot set headers after they are sent to the cl

Answer 1

Sorry for the Late response, As per the mongoose documentation "Mongoose queries are not promises. They have a .then() function for co and async/await as a convenience. However, unlike promises, calling a query's .then() can execute the query multiple time"

so to use promises

mongoose.Promise = global.Promise //To use the native js promises

Then

var promise = Profile.findOne({ user: req.user.id }).exec()
promise.then(function (profile){
    if (!profile) {
      throw new Error("User profile not found") //reject promise with error
    }
    return res.status(200).json(profile) //return user profile      
}).catch(function (err){
    console.log(err); //User profile not found
    return res.status(404).json({ err.message }) //return your error msg
})

here is an nice article about switching out callbacks with promises in Mongoose

and this answer on mongooses promise rejection handling Mongoose right promise rejection handling