CloudFormation stack updates fail due to SSM Command document name conflict

Overview

Customers using AWS CloudFormation to manage their Koha deployments may encounter an issue where stack updates fail with an error message indicating a resource replacement conflict. This occurs specifically when changes are made to the SSM Command document used for configuration application. The failure prevents successful stack updates, potentially disrupting planned configuration changes or updates.

Affected Versions

• Koha AMI builds released before 2026-05-28.

Remediation

The fix is a CloudFormation template change only — you do not need to replace your EC2 instance or migrate data to resolve this issue.

Option 1: Update Your CloudFormation Template (Recommended)

1. In the AWS Marketplace listing, subscribe to or locate your current Koha product.
2. Download the updated CloudFormation template for your tier (Standard or Enterprise).
3. In the AWS CloudFormation console, select your Koha stack → Update → Replace existing template → upload the new template.
4. Proceed through the update wizard. Your EC2 instance and data volume are not replaced — only the SSM document resource is recreated with an auto-generated name.

After the update, future update-stack operations on the SSM document will succeed without a naming conflict.

Option 2: Upgrade to the New AMI

The updated CFN template is also included in the AMI build published 2026-05-27. If you are upgrading your AMI for other reasons, the fix is included automatically.

Option 3: Contact Support

If you need help applying the template update, contact us at [email protected] or use the contact form.

Timeline

References

• KohaSupport Knowledge Base
• Contact KohaSupport