Amazon S3 Bucket Naming Requirements
Please update WHM backup to allow for the latest naming conventions/requirements for Amazon S3 buckets.
All of my buckets have periods in them (e.g., "server.domain.tld"), but WHM disallows periods. This was obviously configured before Amazon adjusted the bucket naming requirements.
I'm not sure why WHM cares about validating the bucket names anyways; if a user inputs an invalid bucket name, it's not going to validate with AWS. Just leave it up to them (AWS/S3) so you don't have to update your software every time a third party changes their standards.
Amazon S3 Bucket Naming Requirements: http://docs.aws.amazon.com/awscloudtrail/latest/userguide/create_trail_naming_policy.html