symfony
diff --git a/‎src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
+2-2 b/‎src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
+2-2
diff --git a/‎src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
+1-2 b/‎src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
+1-2
diff --git a/‎src/Symfony/Component/AssetMapper/ImportMap/ImportMapManager.php
-1 b/‎src/Symfony/Component/AssetMapper/ImportMap/ImportMapManager.php
-1
diff --git a/‎src/Symfony/Component/AssetMapper/ImportMap/ImportMapRenderer.php
+14-3 b/‎src/Symfony/Component/AssetMapper/ImportMap/ImportMapRenderer.php
+14-3
@@ -924,8 +924,8 @@ private function addAssetMapperSection(ArrayNodeDefinition $rootNode, callable $
                             ->defaultValue('%kernel.project_dir%/importmap.php')
                         ->end()
                         ->scalarNode('importmap_polyfill')
-                            ->info('URL of the ES Module Polyfill to use, false to disable. Defaults to using a CDN URL.')
-                            ->defaultValue(null)
+                            ->info('The importmap name that will be used to load the polyfill. Set to false to disable.')
+                            ->defaultValue('es-module-shims')
                         ->end()
                         ->arrayNode('importmap_script_attributes')
                             ->info('Key-value pair of attributes to add to script tags output for the importmap.')
 
@@ -33,7 +33,6 @@
 use Symfony\Component\Asset\PackageInterface;
 use Symfony\Component\AssetMapper\AssetMapper;
 use Symfony\Component\AssetMapper\Compiler\AssetCompilerInterface;
-use Symfony\Component\AssetMapper\ImportMap\ImportMapManager;
 use Symfony\Component\BrowserKit\AbstractBrowser;
 use Symfony\Component\Cache\Adapter\AdapterInterface;
 use Symfony\Component\Cache\Adapter\ArrayAdapter;
@@ -1378,7 +1377,7 @@ private function registerAssetMapperConfiguration(array $config, ContainerBuilde
 
         $container
             ->getDefinition('asset_mapper.importmap.renderer')
-            ->replaceArgument(3, $config['importmap_polyfill'] ?? ImportMapManager::POLYFILL_URL)
+            ->replaceArgument(3, $config['importmap_polyfill'])
             ->replaceArgument(4, $config['importmap_script_attributes'])
         ;
     }
 
@@ -24,7 +24,6 @@
  */
 class ImportMapManager
 {
-    public const POLYFILL_URL = 'https://ga.jspm.io/npm:es-module-shims@1.7.2/dist/es-module-shims.js';
     public const IMPORT_MAP_CACHE_FILENAME = 'importmap.json';
     public const ENTRYPOINT_CACHE_FILENAME_PATTERN = 'entrypoint.%s.json';
 
 
@@ -25,7 +25,7 @@ public function __construct(
         private readonly ImportMapManager $importMapManager,
         private readonly ?Packages $assetPackages = null,
         private readonly string $charset = 'UTF-8',
-        private readonly string|false $polyfillUrl = ImportMapManager::POLYFILL_URL,
+        private readonly string|false $polyfillImportName = false,
         private readonly array $scriptAttributes = [],
     ) {
     }
@@ -38,6 +38,7 @@ public function render(string|array $entryPoint, array $attributes = []): string
         $importMap = [];
         $modulePreloads = [];
         $cssLinks = [];
+        $polyFillPath = null;
         foreach ($importMapData as $importName => $data) {
             $path = $data['path'];
 
@@ -46,6 +47,12 @@ public function render(string|array $entryPoint, array $attributes = []): string
                 $path = $this->assetPackages->getUrl(ltrim($path, '/'));
             }
 
+            // if this represents the polyfill, hide it from the import map
+            if ($importName === $this->polyfillImportName) {
+                $polyFillPath = $path;
+                continue;
+            }
+
             $preload = $data['preload'] ?? false;
             if ('css' !== $data['type']) {
                 $importMap[$importName] = $path;
@@ -76,8 +83,12 @@ public function render(string|array $entryPoint, array $attributes = []): string
             </script>
             HTML;
 
-        if ($this->polyfillUrl) {
-            $url = $this->escapeAttributeValue($this->polyfillUrl);
+        if (false !== $this->polyfillImportName && null === $polyFillPath) {
+            throw new \InvalidArgumentException(sprintf('The JavaScript module polyfill was not found in your import map. Either disable the polyfill or run "php bin/console importmap:require "%s"" to install it.', $this->polyfillImportName));
+        }
+
+        if ($polyFillPath) {
+            $url = $this->escapeAttributeValue($polyFillPath);
 
             $output .= <<<HTML
Original file line number	Diff line number	Diff line change
`@@ -24,7 +24,6 @@`
`24`	`24`	`*/`
`25`	`25`	`class ImportMapManager`
`26`	`26`	`{`
`27`		`- public const POLYFILL_URL = 'https://ga.jspm.io/npm:es-module-shims@1.7.2/dist/es-module-shims.js';`
`28`	`27`	`public const IMPORT_MAP_CACHE_FILENAME = 'importmap.json';`
`29`	`28`	`public const ENTRYPOINT_CACHE_FILENAME_PATTERN = 'entrypoint.%s.json';`
`30`	`29`