The Problem

While attempting to deploy a CloudFormation template from the console, I was greeted by a rather strange error message:

And, for the purposes of searchability:

S3 error: Access Denied For more information check http://docs.aws.amazon.com/AmazonS3/latest/API/ErrorResponses.html

This was after choosing to update a stack by selecting "Replace current template" (1), choosing to "Upload a template file" (2), then choosing the template file (3) and then clicking "Next" (4).

This was also the case when trying to update the stack from the command line but that gave an even more cryptic error message:

> aws cloudformation deploy --stack-name some-stack --template-file some-template.yaml

'NoneType' object has no attribute 'get'

The Solution

As is usually the way, this was a simple one. The template file was empty. A case of not hitting the save button.

But from a bit of poking around, you may also be presented with this error in the case that the template is malformed. I therefore thought it worth mentioning...

HTH