Your company has a number of Cloudformation stacks defined in AWS. As part of the routine housekeeping activity, a number of stacks have been targeted for deletion. But a few of the stacks are not getting deleted and are failing when you are trying to delete them. Which of the following could be valid reasons for this? Choose 2 answers from the options given below

Answer options:

A.The stacks were created with the wrong template version. Since the standard template version is now higher , it is preventing the deletion of the stacks. You need to contact AWS support.
B.The stack has an S3 bucket defined which has objects present in it.
C.The stack has a EC2 Security Group which has EC2 Instances attached to it.
D.The stack consists of an EC2 resource which was created with a custom AMI.

Answer – B and C
The AWS documentation mentions the below point
Some resources must be empty before they can be deleted. For example, you must delete all objects in an Amazon S3 bucket or remove all instances in an Amazon EC2 security group before you can delete the bucket or security group
For more information on troubleshooting cloudformation stacks , please visit the below URL:
http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/troubleshooting.html