Heroku Cannot Get/ when getting data from MongoDB through Heroku API Using MEN Stack

js express server and Heroku API hosting.

I created a backend that allows me to post and get data from MongoDB through express server that is hosted on Heroku , I’m using postman for testing.

POST method works well both locally and on Heroku.
GET method only works locally and I get A Cannot GET / error with a 404 code when I test on Heroku.

This is my code below:

router.get('/posts', async (req, res) => {
    try {
        const posts = await Posts.find();
        res.json(posts)
        console.log('data',res.send)
    }catch (err) {
        res.send('error', err)
    }
});

module.exports = router;