diff --git a/src/Symfony/Bridge/Doctrine/DependencyInjection/AbstractDoctrineExtension.php b/src/Symfony/Bridge/Doctrine/DependencyInjection/AbstractDoctrineExtension.php
index 00652bb71612..34aba14e9f6e 100644
--- a/src/Symfony/Bridge/Doctrine/DependencyInjection/AbstractDoctrineExtension.php
+++ b/src/Symfony/Bridge/Doctrine/DependencyInjection/AbstractDoctrineExtension.php
@@ -11,6 +11,7 @@
 
 namespace Symfony\Bridge\Doctrine\DependencyInjection;
 
+use Symfony\Component\Config\Resource\GlobResource;
 use Symfony\Component\DependencyInjection\Alias;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Definition;
@@ -88,6 +89,25 @@ protected function loadMappingInformation(array $objectManager, ContainerBuilder
                 if (!$mappingConfig) {
                     continue;
                 }
+            } elseif (!$mappingConfig['type'] && \PHP_VERSION_ID < 80000) {
+                $mappingConfig['type'] = 'annotation';
+            } elseif (!$mappingConfig['type']) {
+                $mappingConfig['type'] = 'attribute';
+
+                $glob = new GlobResource($mappingConfig['dir'], '*', true);
+                $container->addResource($glob);
+
+                foreach ($glob as $file) {
+                    $content = file_get_contents($file);
+
+                    if (preg_match('/^#\[.*Entity\b/m', $content)) {
+                        break;
+                    }
+                    if (preg_match('/^ \* @.*Entity\b/m', $content)) {
+                        $mappingConfig['type'] = 'annotation';
+                        break;
+                    }
+                }
             }
 
             $this->assertValidMappingConfiguration($mappingConfig, $objectManager['name']);
diff --git a/src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_4_layout.html.twig b/src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_4_layout.html.twig
index b279477265bf..343c8e17455c 100644
--- a/src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_4_layout.html.twig
+++ b/src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_4_layout.html.twig
@@ -125,7 +125,7 @@
         {% if app is defined and app.request is defined %}{%- set input_lang = app.request.locale -%}{%- endif -%}
         {%- set attr = {lang: input_lang} | merge(attr) -%}
         {{- block('form_widget_simple') -}}
-        {%- set label_attr = label_attr|merge({ class: (label_attr.class|default('') ~ ' custom-file-label')|trim }) -%}
+        {%- set label_attr = label_attr|merge({ class: (label_attr.class|default('') ~ ' custom-file-label')|trim })|filter((value, key) => key != 'id') -%}
         <label for="{{ form.vars.id }}" {% with { attr: label_attr } %}{{ block('attributes') }}{% endwith %}>
             {%- if attr.placeholder is defined and attr.placeholder is not none -%}
                 {{- translation_domain is same as(false) ? attr.placeholder : attr.placeholder|trans({}, translation_domain) -}}
diff --git a/src/Symfony/Bridge/Twig/Tests/Extension/AbstractBootstrap4LayoutTest.php b/src/Symfony/Bridge/Twig/Tests/Extension/AbstractBootstrap4LayoutTest.php
index 4c92d628850e..61006607c33e 100644
--- a/src/Symfony/Bridge/Twig/Tests/Extension/AbstractBootstrap4LayoutTest.php
+++ b/src/Symfony/Bridge/Twig/Tests/Extension/AbstractBootstrap4LayoutTest.php
@@ -1121,6 +1121,24 @@ public function testFile()
         );
     }
 
+    public function testFileLabelIdNotDuplicated()
+    {
+        $form = $this->factory->createNamed('name', FileType::class);
+
+        $this->assertWidgetMatchesXpath($form->createView(), ['id' => 'n/a', 'attr' => ['class' => 'my&class form-control-file'], 'label_attr' => ['id' => 'label-id']],
+'/div
+    [@class="custom-file"]
+    [
+        ./input
+            [@type="file"]
+            [@name="name"]
+        /following-sibling::label
+            [@for="name"][not(@id)]
+    ]
+'
+        );
+    }
+
     public function testFileWithPlaceholder()
     {
         $form = $this->factory->createNamed('name', FileType::class);