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Not Found or 404 is not by default an application err, the handler which you have defined gets called only when you pass the error in the next argument of any route. For handling 404 You should use a handler without err

app.use(function(req, res, next) {
   // Do logging and user-friendly error message display
   console.log('Route does not exist')
   res.status(500).send({ status:500, message: 'internal error',type:'internal' })
})

Note:- Above handler should be placed after all the valid routes and above the error handler.

if however, you want to handle both 404 and other errors with same response you could explicitly generate error for 404, Something like:

    app.get('/someRoute',function(req,res,next){
       //if some error occures pass the error to next.
       next(new Error('error'))
       // otherwise just return the response
    })   

    app.use(function(req, res, next) {
           // Do logging and user-friendly error message display
           console.log('Route does not exist')
           next(new Error('Not Found'))
    })

    app.use(function(err, req, res, next) {
        // Do logging and user-friendly error message display
        console.error(err)
        res.status(500).send({ status:500, message: 'internal error', 
        type:'internal' })
    })

This way your error handler is also called for not found errors and for all the other business logic errors

Not Found or 404 is not by default an application error, the handler which you have to define gets called only when you pass the error in the next argument of any route. For handling 404, you should use a handler without an error.

app.use(function(req, res, next) {
   // Do logging and user-friendly error message display.
   console.log('Route does not exist')
   res.status(500).send({
       status: 500,
       message: 'internal error',
       type: 'internal'
   })
})

Note: The above handler should be placed after all the valid routes and above the error handler.

If, however, you want to handle both 404 and other errors with same response you could explicitly generate an error for 404. For instance:

app.get('/someRoute',function(req, res, next) {
   // If some error occurs pass the error to next.
   next(new Error('error'))
   // Otherwise just return the response.
})   

app.use(function(req, res, next) {
   // Do logging and user-friendly error message display.
   console.log('Route does not exist')
   next(new Error('Not Found'))
})

app.use(function(err, req, res, next) {
    // Do logging and user-friendly error message display
    console.error(err)
    res.status(500).send({
        status: 500,
        message: 'internal error', 
        type: 'internal'
    })
})

This way, your error handler is also called for not found errors and for all the other business logic errors.

Not Found or 404 is not by default an application err, the handler which you have defined gets called only when you pass the error in next argument of any route. For handling 404 You should use a handler without err

app.use(function(req, res, next) {
   // Do logging and user-friendly error message display
   console.log('Route does not exist')
   res.status(500).send({status:500, message: 'internal error',type:'internal'}); 
})

Note:- Above handler should be placed after all the valid routes and above the error handler.

if however, you want to handle both 404 and other errors with same response you could explicitly generate error for 404, Something like:

    app.get('/someRoute,function(req,res,next){
       //if some error occures pass the error to next.
       next(new Error('error'))
       // otherwise just return the response
    })   

    app.use(function(req, res, next) {
           // Do logging and user-friendly error message display
           console.log('Route does not exist')
           next(new Error('Not Found'))
    })

    app.use(function(err, req, res, next) {
        // Do logging and user-friendly error message display
        console.error(err);
        res.status(500).send({status:500, message: 'internal error', 
        type:'internal'}); 
    })

This way your error handler is also called for not found errors and for all the other business logic errors

Not Found or 404 is not by default an application err, the handler which you have defined gets called only when you pass the error in the next argument of any route. For handling 404 You should use a handler without err

app.use(function(req, res, next) {
   // Do logging and user-friendly error message display
   console.log('Route does not exist')
   res.status(500).send({ status:500, message: 'internal error',type:'internal' })
})

Note:- Above handler should be placed after all the valid routes and above the error handler.

if however, you want to handle both 404 and other errors with same response you could explicitly generate error for 404, Something like:

    app.get('/someRoute',function(req,res,next){
       //if some error occures pass the error to next.
       next(new Error('error'))
       // otherwise just return the response
    })   

    app.use(function(req, res, next) {
           // Do logging and user-friendly error message display
           console.log('Route does not exist')
           next(new Error('Not Found'))
    })

    app.use(function(err, req, res, next) {
        // Do logging and user-friendly error message display
        console.error(err)
        res.status(500).send({ status:500, message: 'internal error', 
        type:'internal' })
    })

This way your error handler is also called for not found errors and for all the other business logic errors

Not Found or 404 is not by default an application err, the handler which you have defined gets called only when some application error has occurred.For handling 404 You should use a handler without err

app.use(function(req, res, next) {
   // Do logging and user-friendly error message display
   console.log('Route does not exist')
   res.status(500).send({status:500, message: 'internal error',type:'internal'}); 
})

Note:- Above handler should be placed after all the valid routes and above the error handler.

if however, you want to handle both 404 and other errors with same response you could explicitly generate error for 404, Something like:

    app.use(function(req, res, next) {
           // Do logging and user-friendly error message display
           console.log('Route does not exist')
           next(new Error('Not Found'))
    })

    app.use(function(err, req, res, next) {
        // Do logging and user-friendly error message display
        console.error(err);
        res.status(500).send({status:500, message: 'internal error', 
        type:'internal'}); 
    })

This way your error handler is also called for not found errors

Not Found or 404 is not by default an application err, the handler which you have defined gets called only when you pass the error in next argument of any route. For handling 404 You should use a handler without err

app.use(function(req, res, next) {
   // Do logging and user-friendly error message display
   console.log('Route does not exist')
   res.status(500).send({status:500, message: 'internal error',type:'internal'}); 
})

Note:- Above handler should be placed after all the valid routes and above the error handler.

if however, you want to handle both 404 and other errors with same response you could explicitly generate error for 404, Something like:

    app.get('/someRoute,function(req,res,next){
       //if some error occures pass the error to next.
       next(new Error('error'))
       // otherwise just return the response
    })   

    app.use(function(req, res, next) {
           // Do logging and user-friendly error message display
           console.log('Route does not exist')
           next(new Error('Not Found'))
    })

    app.use(function(err, req, res, next) {
        // Do logging and user-friendly error message display
        console.error(err);
        res.status(500).send({status:500, message: 'internal error', 
        type:'internal'}); 
    })

This way your error handler is also called for not found errors and for all the other business logic errors