Unable to create a stage in AWS API Gateway

This happens when you don't have any deployment for you API. You could deploy your API and create new stage.

Make sure you do not have any resources created without their integration method defined. It does not allow you to create a stag or deploy your api gateway until you define integration method for all your resource methods.

To expand on Zoey Sun's answer:

If you don't have any deployments, you need to create one, which it seems can only be done when you actually deploy your API. So under your API, got to the 'Resources' tab, use the Actions dropdown. It's in this UI that you'll get the option to create a new stage. If you get warned about not having any integrations, just add a simple action like an HTTP pass through.

So you're effectively deploying before you've built it. I agree with the comments not very intuitive.

This happens because you have never deployed your API. You would need to deploy your API first by doing the following:

1. From AWS Console go to API Gateway
2. Select your API by clicking on your API name.
3. (If not already selected) Click on the Resources menu on the left hand side of the screen.
4. Click on the resources "Actions" menu and select "Deploy API"
5. On the popup modal page fill out the fields Deployment Stage [New Stage] Stage Name:
6. Click the "Deploy" button