Have you specified a start command? For example if this is a nodejs app then you need to add your start command in your package.json file

no , i have not specified it , but its a flask app , i cant find config file to add it

You'd want to run your flask app via gunicorn

Copy and pasting this railway.json file into your project should do the trick https://github.com/railwayapp-templates/flask/blob/main/railway.json (make sure you have gunicorn specified in your requirements.txt)