Google App Engine: Can't create second app on same developer machine ("The project already contains an App Engine application")

You can create only one App Engine app per Google Cloud project.

If your new project is related to the old one, You can create a new App Engine service in the same Google Cloud project: In your app.yaml, you can specify a service name: service: [SERVICE_NAME]. Now when you run gcloud app deploy, it will deploy a new service to the same project.

If your new project is not related to the old one, you should just create a new Cloud Console project and then create an App Engine app for this one. To do so, either use the command line: gcloud projects create [PROJECT_ID] or simply browse to https://console.cloud.google.com to create it. Then, you can either:

• use gcloud app deploy app.yaml --project [PROJECT_ID] to deploy to this project.
• tell gcloud that you are now working within that project: gcloud config set project [PROJECT_ID]