diff --git a/manifest.json b/manifest.json
index 60fe4ea3b..4949e1750 100644
--- a/manifest.json
+++ b/manifest.json
@@ -1,6 +1,6 @@
 {
     "variables": {
-        "${LATEST}": "3.342.2"
+        "${LATEST}": "3.342.3"
     },
     "endpoints": "https://raw.githubusercontent.com/aws/aws-sdk-php/${LATEST}/src/data/endpoints.json",
     "services": {
diff --git a/src/Service/Sns/CHANGELOG.md b/src/Service/Sns/CHANGELOG.md
index b99970f0f..ffbfe3079 100644
--- a/src/Service/Sns/CHANGELOG.md
+++ b/src/Service/Sns/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## NOT RELEASED
 
+### Added
+
+- AWS api-change: Make supported regions explicit
+
 ## 1.8.0
 
 ### Added
diff --git a/src/Service/Sns/composer.json b/src/Service/Sns/composer.json
index e061f2493..d6424f3fa 100644
--- a/src/Service/Sns/composer.json
+++ b/src/Service/Sns/composer.json
@@ -28,7 +28,7 @@
     },
     "extra": {
         "branch-alias": {
-            "dev-master": "1.8-dev"
+            "dev-master": "1.9-dev"
         }
     }
 }
diff --git a/src/Service/Sns/src/SnsClient.php b/src/Service/Sns/src/SnsClient.php
index 34c9102b2..63dd3fef2 100644
--- a/src/Service/Sns/src/SnsClient.php
+++ b/src/Service/Sns/src/SnsClient.php
@@ -6,6 +6,7 @@
 use AsyncAws\Core\AwsError\AwsErrorFactoryInterface;
 use AsyncAws\Core\AwsError\XmlAwsErrorFactory;
 use AsyncAws\Core\Configuration;
+use AsyncAws\Core\Exception\UnsupportedRegion;
 use AsyncAws\Core\RequestContext;
 use AsyncAws\Core\Result;
 use AsyncAws\Sns\Exception\AuthorizationErrorException;
@@ -547,6 +548,44 @@ protected function getEndpointMetadata(?string $region): array
         }
 
         switch ($region) {
+            case 'af-south-1':
+            case 'ap-east-1':
+            case 'ap-northeast-1':
+            case 'ap-northeast-2':
+            case 'ap-northeast-3':
+            case 'ap-south-1':
+            case 'ap-south-2':
+            case 'ap-southeast-1':
+            case 'ap-southeast-2':
+            case 'ap-southeast-3':
+            case 'ap-southeast-4':
+            case 'ap-southeast-5':
+            case 'ap-southeast-7':
+            case 'ca-central-1':
+            case 'ca-west-1':
+            case 'eu-central-1':
+            case 'eu-central-2':
+            case 'eu-north-1':
+            case 'eu-south-1':
+            case 'eu-south-2':
+            case 'eu-west-1':
+            case 'eu-west-2':
+            case 'eu-west-3':
+            case 'il-central-1':
+            case 'me-central-1':
+            case 'me-south-1':
+            case 'mx-central-1':
+            case 'sa-east-1':
+            case 'us-east-1':
+            case 'us-east-2':
+            case 'us-west-1':
+            case 'us-west-2':
+                return [
+                    'endpoint' => "https://sns.$region.amazonaws.com",
+                    'signRegion' => $region,
+                    'signService' => 'sns',
+                    'signVersions' => ['v4'],
+                ];
             case 'cn-north-1':
             case 'cn-northwest-1':
                 return [
@@ -591,6 +630,7 @@ protected function getEndpointMetadata(?string $region): array
                     'signVersions' => ['v4'],
                 ];
             case 'fips-us-gov-east-1':
+            case 'us-gov-east-1':
                 return [
                     'endpoint' => 'https://sns.us-gov-east-1.amazonaws.com',
                     'signRegion' => 'us-gov-east-1',
@@ -598,6 +638,7 @@ protected function getEndpointMetadata(?string $region): array
                     'signVersions' => ['v4'],
                 ];
             case 'fips-us-gov-west-1':
+            case 'us-gov-west-1':
                 return [
                     'endpoint' => 'https://sns.us-gov-west-1.amazonaws.com',
                     'signRegion' => 'us-gov-west-1',
@@ -629,11 +670,6 @@ protected function getEndpointMetadata(?string $region): array
                 ];
         }
 
-        return [
-            'endpoint' => "https://sns.$region.amazonaws.com",
-            'signRegion' => $region,
-            'signService' => 'sns',
-            'signVersions' => ['v4'],
-        ];
+        throw new UnsupportedRegion(\sprintf('The region "%s" is not supported by "Sns".', $region));
     }
 }