Cloudformation submitted information does not contain changes when updating task formation image version - aws-cloudformation

Question

If my cloud formation script is like this:
myServiceName:
Type: "AWS::ECS::Service"
Properties:
ServiceName: "myServiceName"
TaskDefinition: !Ref myTaskName
myTaskName:
Type: "AWS::ECS::TaskDefinition"
Properties:
ContainerDefinitions:
Image: !Sub "${AWS::AccountId}.dkr.ecr.${AWS::Region}.amazonaws.com/docker-image-name:1.1.1"
And I update the task definition to 1.1.2
Image: !Sub "${AWS::AccountId}.dkr.ecr.${AWS::Region}.amazonaws.com/docker-image-name:1.1.2"
Then trying to run a Cloud formation update command gives me this error:
*Submitted information does not contain changes. *
Is it just not possible to update the task definition to point to a new image in an ecr with out changing the service?

Answer 1

All the documentation I've read says that this error comes up when you don't change any properties of your resource, so Cloudformation doesn't see any resources as changed, and therefore won't redeploy.
But you are changing a property, and yet it's still happening, which is weird. I haven't been able to find any record of such behavior.
Debugging suggestion: try adding an arbitrary new property to your resource, e.g. a tag field. If it updates successfully, it means for some reason the changed Image doesn't trigger an update, and the fix would be to always change something else too. If it still doesn't update, then I suspect something is going wrong somewhere else in your process and you're not actually uploading your changed template at all.

Answer 2

I found the following in the CloudFormation User Guide that may help.
Troubleshooting CloudFormation - No updates to perform
I encountered an issue adding a DeletionPolicy attribute (which is not a property). According to the documentation, adding/changing metadata will cause CloudFormation to accept certain changes.