Failed to change Systems Manager delegated administrator account

I understand you're having difficulty changing the Systems Manager delegated administrator account for your organization. This is a complex process that can sometimes encounter issues. Let me provide some insights and potential solutions based on the information you've shared.

First, it's important to note that changing a delegated administrator account for Systems Manager is not as simple as just disabling the organizational setup. The process typically involves deregistering the current delegated administrator and then registering a new one.

The error messages you're seeing suggest that there might be some underlying configuration issues preventing the change. Here are a few things to consider:

1. Ensure that the new account you want to set as the delegated administrator meets all the necessary requirements. It should be part of your organization, and it must be the only member of the organizational unit (OU) to which it's assigned in AWS Organizations.

2. Verify that you have the necessary permissions to make this change. Typically, these actions need to be performed from the AWS Organizations management account.

3. Check if there are any active change requests or ongoing operations in Change Manager (a capability of Systems Manager) that might be interfering with the process.

4. Make sure that all features in your organization are enabled, as this is a prerequisite for designating a new delegated administrator.

5. If you're using Change Manager across your organization, remember that changes should ideally be made from the current delegated administrator account until the new one is successfully set up.

If you continue to encounter issues, you may need to contact AWS Support for further assistance. They can provide more detailed diagnostics and help resolve any underlying problems that aren't visible through the Diagnose and remediate tool.

Remember, when you do successfully change the delegated administrator, you'll need to reconfigure all job functions and permissions in the new account. It's a significant change that requires careful planning and execution.
Sources
AWS Systems Manager Change Manager - AWS Systems Manager
Setting up Change Manager for an organization (management account) - AWS Systems Manager
Changing a delegated administrator - AWS Audit Manager