This is the answer to "How to kill a process based on port number?"

Kill a process based on port number

If you close out VS Code with an active live-server running, it may keep the server process alive and you won't be able to create a new server, just by opening a new VS Code project.

If you find yourself getting errors when trying to run live-server, you may need to kill an old process running in the background. The command to do this vary depending on operating system interface. Note that live-server run on port 5500 by default.

Windows DOS Commands

netstat -ano | findstr :5500

taskkill /PID <process ID> /F

Windows Powershell Commands

netstat -a -b -n -o
Stop-Process <pid>

You can also run resmon.exe to find the process ID.

Mac OS X Commands

lsof -i :5500

kill -9 <pid>