For example it’s the first time for you to run PHP in VS Code, the VS Code may prompt that you need to set a validate executable path firstly in the setting.json, it’s easy to manage it as below:
e.g.
your php is installed already(I have already installed the Xampp which contains the PHP component) and it’s path is “C:\Xampp\Php\php.exe”, you just open the setting.json and paste the following information
C:/xampp/php/php.exe
Just save it and the VS will run well.