diff --git a/clients/client-cognito-identity-provider/src/models/models_1.ts b/clients/client-cognito-identity-provider/src/models/models_1.ts
index 4976311fbb69..7db7e08226d2 100644
--- a/clients/client-cognito-identity-provider/src/models/models_1.ts
+++ b/clients/client-cognito-identity-provider/src/models/models_1.ts
@@ -3483,7 +3483,7 @@ export interface UpdateUserPoolDomainRequest {
    *             in a <a href="https://docs.aws.amazon.com/cognito-user-identity-pools/latest/APIReference/API_SetUserPoolMfaConfig.html">SetUserPoolMfaConfig</a> request.</p>
    * @public
    */
-  CustomDomainConfig: CustomDomainConfigType | undefined;
+  CustomDomainConfig?: CustomDomainConfigType | undefined;
 }
 
 /**
diff --git a/codegen/sdk-codegen/aws-models/cognito-identity-provider.json b/codegen/sdk-codegen/aws-models/cognito-identity-provider.json
index e753dd8ce89f..06352bd7b491 100644
--- a/codegen/sdk-codegen/aws-models/cognito-identity-provider.json
+++ b/codegen/sdk-codegen/aws-models/cognito-identity-provider.json
@@ -16209,8 +16209,7 @@
         "CustomDomainConfig": {
           "target": "com.amazonaws.cognitoidentityprovider#CustomDomainConfigType",
           "traits": {
-            "smithy.api#documentation": "<p>The configuration for a custom domain that hosts the sign-up and sign-in pages for\n            your application. Use this object to specify an SSL certificate that is managed by\n            ACM.</p>\n         <p>When you create a custom domain, the passkey RP ID defaults to the custom domain. If\n            you had a prefix domain active, this will cause passkey integration for your prefix\n            domain to stop working due to a mismatch in RP ID. To keep the prefix domain passkey\n            integration working, you can explicitly set RP ID to the prefix domain. Update the RP ID\n            in a <a href=\"https://docs.aws.amazon.com/cognito-user-identity-pools/latest/APIReference/API_SetUserPoolMfaConfig.html\">SetUserPoolMfaConfig</a> request.</p>",
-            "smithy.api#required": {}
+            "smithy.api#documentation": "<p>The configuration for a custom domain that hosts the sign-up and sign-in pages for\n            your application. Use this object to specify an SSL certificate that is managed by\n            ACM.</p>\n         <p>When you create a custom domain, the passkey RP ID defaults to the custom domain. If\n            you had a prefix domain active, this will cause passkey integration for your prefix\n            domain to stop working due to a mismatch in RP ID. To keep the prefix domain passkey\n            integration working, you can explicitly set RP ID to the prefix domain. Update the RP ID\n            in a <a href=\"https://docs.aws.amazon.com/cognito-user-identity-pools/latest/APIReference/API_SetUserPoolMfaConfig.html\">SetUserPoolMfaConfig</a> request.</p>"
           }
         }
       },