How do I resolve the CloudFormation error "Cannot update a stack when a custom-named resource requires replacing"?

Short description

This error occurs when a stack update tries to replace resources that have properties with custom names. CloudFormation doesn't replace a resource that has a custom name unless that custom name is changed to a different name. To prevent a stack failure, before you update a stack, be sure that you change any resources with custom names to use different names.

The resolution for this error assumes the following:

• You're updating an existing stack and not creating a new stack.
• You're changing the names of existing custom-named resources and not creating new custom-named resources.

Resolution

1. In a code editor, open the CloudFormation template for the stack that you want to update.

2. Replace the names or values of any resource properties that have custom names to use different names.

   Note: In the following example, the DBInstanceIdentifier property of the MyRDS resource is set to the custom name PRODdb. The CloudFormation stack can't be updated until the name PRODdb is changed to a different name, such as PRODdb1. Or, omit the DBInstanceIdentifier property from your template so that CloudFormation generates a unique physical ID to use for the DB instance.

   "MyRDS": {    "Type": "AWS::RDS::DBInstance",
       "Properties": {
           "DBInstanceClass": "db.m3.medium",
           "Engine": "MySQL",
           "DBInstanceIdentifier": "PRODdb",
           "AllocatedStorage": "10",
           "AutoMinorVersionUpgrade": "true",
           "BackupRetentionPeriod": "0",
       . . . 
       . . .
       }
   }

   Important: When you rename a custom-named resource, CloudFormation replaces that resource. For more information, see Name type. Replacement of certain resources can cause data loss without proper backup. For more information, see Replacement.

3. Save the changes to your CloudFormation template, and then use the template to update your stack.

Related information

Managing AWS resources as a single unit with CloudFormation stacks

Understand update behaviors of stack resources

AWS resource and property types reference