What could cause this attempt to be unsuccessful?
No multi-factor authentication (MFA) has been configured.
The root user is not specifically assigned to the administration group.
The root user’s password does not meet the minimum password complexity requirements.
The organizational administrator has used a service control policy (SCP) to limit the root user permissions.
Explanations:
Multi-factor authentication (MFA) is not a requirement for closing an AWS account, although it is a best practice for securing the root user account. The absence of MFA would not directly prevent the account closure attempt.
The root user does not need to be assigned to a specific group to perform actions such as closing an account. The root user has full access to all resources and services in the account, regardless of group assignments.
Password complexity requirements apply to IAM users but not to the root user credentials. The root user’s password does not need to meet these requirements in the same way as IAM users. Therefore, this would not prevent closing the account.
Service Control Policies (SCPs) can restrict the actions of accounts within an AWS Organization, including actions taken by the root user. If the organizational administrator has implemented a policy that limits the permissions of the root user, this would prevent the account from being closed successfully.
I classify that the answer is:
The organizational administrator has used a service control policy (SCP) to limit the root user permissions.