In package.json, make sure you add -p $PORT at the start script.
"scripts": {
"start": "next start -p $PORT"
}Heroku dynamically assigns your app a port, so you can't set the port to a fixed number. Heroku adds the port to the env, so you can pull it from there. Switch your listen to this:
.listen(process.env.PORT || 5000)
That way it'll still listen to port 5000 when you test locally, but it will also work on Heroku.In package.json,, make sur you add -p $PORT at the start script.
"scripts": {
"start": "next start -p $PORT"
}.listen(process.env.PORT || 5000)heroku port