How can I stop a symfony process which is listening on http://127.0.0.1:8000

Better to use killall -9 php to kill all php scripts that are running. Otherwise you wil start a new one while the previous one is still running.

Is probably caused by a infinite loop.

Note: This will "kill" all running php scripts

You can stop the server using:

php bin/console server:stop

or you can force server to start even if previous one is running:

php bin/console server:start --force

For more info check the doc

This works on Symfony 5. Open the integrated terminal inside VSCode.

First stop the running local server:

symfony local:server:stop

Then start a new one:

symfony server:start

Open your browser and navigate to: 127.0.0.1:8000

If the command symfony is not recognized, then you need to install the Symfony as instructed here: Install Symfony