diff --git a/src/StimulusBundle/src/AssetMapper/ControllersMapGenerator.php b/src/StimulusBundle/src/AssetMapper/ControllersMapGenerator.php
index b99f5ffbe5c..9799cdd3ec1 100644
--- a/src/StimulusBundle/src/AssetMapper/ControllersMapGenerator.php
+++ b/src/StimulusBundle/src/AssetMapper/ControllersMapGenerator.php
@@ -70,6 +70,11 @@ private function loadCustomControllers(): array
 
         $controllersMap = [];
         foreach ($finder as $file) {
+            // Skip .ts controller if .js version is available
+            if ('ts' === $file->getExtension() && file_exists(substr($file->getRealPath(), 0, -2).'js')) {
+                continue;
+            }
+
             $name = $file->getRelativePathname();
             // use regex to extract 'controller'-postfix including extension
             preg_match(self::FILENAME_REGEX, $name, $matches);
@@ -77,6 +82,10 @@ private function loadCustomControllers(): array
             $name = str_replace(['_', '/', '\\'], ['-', '--', '--'], $name);
 
             $asset = $this->assetMapper->getAssetFromSourcePath($file->getRealPath());
+            if (!$asset) {
+                throw new \RuntimeException(\sprintf('Could not find an asset mapper path that points to the "%s" controller.', $name));
+            }
+
             $content = file_get_contents($asset->sourcePath);
             $isLazy = preg_match('/\/\*\s*stimulusFetch:\s*\'lazy\'\s*\*\//i', $content);
 
diff --git a/src/StimulusBundle/tests/AssetMapper/ControllersMapGeneratorTest.php b/src/StimulusBundle/tests/AssetMapper/ControllersMapGeneratorTest.php
index 21277b28003..15004969447 100644
--- a/src/StimulusBundle/tests/AssetMapper/ControllersMapGeneratorTest.php
+++ b/src/StimulusBundle/tests/AssetMapper/ControllersMapGeneratorTest.php
@@ -34,6 +34,8 @@ public function testGetControllersMap()
                     $logicalPath = 'fake-vendor/ux-package1/package-controller-second.js';
                 } elseif (str_ends_with($path, 'package-hello-controller.js')) {
                     $logicalPath = 'fake-vendor/ux-package2/package-hello-controller.js';
+                } elseif (str_ends_with($path, 'other-controller.ts') || str_ends_with($path, 'excluded-controller.js')) {
+                    return null;
                 } else {
                     // replace windows slashes
                     $path = str_replace('\\', '/', $path);
@@ -75,15 +77,18 @@ public function testGetControllersMap()
             $autoImportLocator,
         );
 
+        $this->expectException(\RuntimeException::class);
+        $this->expectExceptionMessage('Could not find an asset mapper path that points to the "excluded" controller.');
         $map = $generator->getControllersMap();
         // + 3 controller.json UX controllers
         // - 1 controllers.json UX controller is disabled
-        // + 10 custom controllers (1 file is not a controller & 1 is overridden)
-        $this->assertCount(12, $map);
+        // + 11 custom controllers (1 file is not a controller, 1 is overridden)
+        $this->assertCount(13, $map);
         $packageNames = array_keys($map);
         sort($packageNames);
         $this->assertSame([
             'bye',
+            'excluded',
             'fake-vendor--ux-package1--controller-second',
             'fake-vendor--ux-package2--hello-controller',
             'hello',
diff --git a/src/StimulusBundle/tests/AssetMapper/StimulusControllerLoaderFunctionalTest.php b/src/StimulusBundle/tests/AssetMapper/StimulusControllerLoaderFunctionalTest.php
index 58bb6c8c97c..346fca2fa32 100644
--- a/src/StimulusBundle/tests/AssetMapper/StimulusControllerLoaderFunctionalTest.php
+++ b/src/StimulusBundle/tests/AssetMapper/StimulusControllerLoaderFunctionalTest.php
@@ -63,7 +63,8 @@ public function testFullApplicationLoad()
                 // 2x from UX packages, which are enabled in controllers.json
                 '/assets/fake-vendor/ux-package1/package-controller-second.js',
                 '/assets/fake-vendor/ux-package2/package-hello-controller.js',
-                // 3x from more-controllers
+                // 4x from more-controllers
+                '/assets/more-controllers/excluded-controller.js',
                 '/assets/more-controllers/hello-controller.js',
                 '/assets/more-controllers/minified-controller.js',
                 '/assets/more-controllers/other-controller.js',
diff --git a/src/StimulusBundle/tests/fixtures/assets/more-controllers/excluded-controller.js b/src/StimulusBundle/tests/fixtures/assets/more-controllers/excluded-controller.js
new file mode 100644
index 00000000000..967c4832525
--- /dev/null
+++ b/src/StimulusBundle/tests/fixtures/assets/more-controllers/excluded-controller.js
@@ -0,0 +1,6 @@
+// excluded-controller.js
+import { Controller } from '@hotwired/stimulus';
+
+/*    stimulusFetch:    'lazy'   */
+export default class extends Controller {
+}
diff --git a/src/StimulusBundle/tests/fixtures/assets/more-controllers/other-controller.ts b/src/StimulusBundle/tests/fixtures/assets/more-controllers/other-controller.ts
new file mode 100644
index 00000000000..1e6f9ccdbc6
--- /dev/null
+++ b/src/StimulusBundle/tests/fixtures/assets/more-controllers/other-controller.ts
@@ -0,0 +1,7 @@
+// other-controller.js
+// @ts-ignore
+import { Controller } from '@hotwired/stimulus';
+
+/*    stimulusFetch:    'lazy'   */
+export default class extends Controller {
+}