Node.js app can't run on port 80 even though there's no other process blocking the port
Solution 1:
The error code EACCES means you don't have proper permissions to run applications on that port. On Linux systems, any port below 1024 requires root access.
Solution 2:
Instead of running on port 80 you can redirect port 80 to your application's port (>1024) using
iptables -t nat -I PREROUTING -p tcp --dport 80 -j REDIRECT --to-port 3000
This will work if your application is running on port 3000.