diff --git a/UPGRADE-4.3.md b/UPGRADE-4.3.md
index 8050fed267..7a2dca2063 100644
--- a/UPGRADE-4.3.md
+++ b/UPGRADE-4.3.md
@@ -23,6 +23,7 @@ Config
 Form
 ----
 
+ * Using the `format` option of `DateType` and `DateTimeType` when the `html5` option is enabled is deprecated.
  * Using names for buttons that do not start with a letter, a digit, or an underscore is deprecated and will lead to an
    exception in 5.0.
  * Using names for buttons that do not contain only letters, digits, underscores, hyphens, and colons is deprecated and
diff --git a/UPGRADE-5.0.md b/UPGRADE-5.0.md
index 07a21d558b..f61211c1cc 100644
--- a/UPGRADE-5.0.md
+++ b/UPGRADE-5.0.md
@@ -78,6 +78,7 @@ Finder
 Form
 ----
  
+ * Removed support for using the `format` option of `DateType` and `DateTimeType` when the `html5` option is enabled.
  * Using names for buttons that do not start with a letter, a digit, or an underscore leads to an exception.
  * Using names for buttons that do not contain only letters, digits, underscores, hyphens, and colons leads to an
    exception.
diff --git a/src/Symfony/Component/Form/CHANGELOG.md b/src/Symfony/Component/Form/CHANGELOG.md
index 2304727571..d25fbc6a4c 100644
--- a/src/Symfony/Component/Form/CHANGELOG.md
+++ b/src/Symfony/Component/Form/CHANGELOG.md
@@ -4,6 +4,7 @@ CHANGELOG
 4.3.0
 -----
 
+ * Using the `format` option of `DateType` and `DateTimeType` when the `html5` option is enabled is deprecated.
  * Using names for buttons that do not start with a letter, a digit, or an underscore is deprecated and will lead to an
    exception in 5.0.
  * Using names for buttons that do not contain only letters, digits, underscores, hyphens, and colons is deprecated and
diff --git a/src/Symfony/Component/Form/Extension/Core/Type/DateTimeType.php b/src/Symfony/Component/Form/Extension/Core/Type/DateTimeType.php
index 291d86af6f..4e84b71a7c 100644
--- a/src/Symfony/Component/Form/Extension/Core/Type/DateTimeType.php
+++ b/src/Symfony/Component/Form/Extension/Core/Type/DateTimeType.php
@@ -159,6 +159,10 @@ class DateTimeType extends AbstractType
             $dateOptions['input'] = $timeOptions['input'] = 'array';
             $dateOptions['error_bubbling'] = $timeOptions['error_bubbling'] = true;
 
+            if (isset($dateOptions['format']) && DateType::HTML5_FORMAT !== $dateOptions['format']) {
+                $dateOptions['html5'] = false;
+            }
+
             $builder
                 ->addViewTransformer(new DataTransformerChain([
                     new DateTimeToArrayTransformer($options['model_timezone'], $options['view_timezone'], $parts),
@@ -294,6 +298,8 @@ class DateTimeType extends AbstractType
             'choice',
         ]);
 
+        $resolver->setAllowedTypes('input_format', 'string');
+
         $resolver->setDeprecated('date_format', function (Options $options, $dateFormat) {
             if (null !== $dateFormat && 'single_text' === $options['widget'] && self::HTML5_FORMAT === $options['format']) {
                 return sprintf('Using the "date_format" option of %s with an HTML5 date widget is deprecated since Symfony 4.3 and will lead to an exception in 5.0.', self::class);
@@ -318,8 +324,14 @@ class DateTimeType extends AbstractType
 
             return '';
         });
+        $resolver->setDeprecated('html5', function (Options $options, $html5) {
+            if ($html5 && self::HTML5_FORMAT !== $options['format']) {
+                return sprintf('Using a custom format when the "html5" option of %s is enabled is deprecated since Symfony 4.3 and will lead to an exception in 5.0.', self::class);
+                //throw new LogicException(sprintf('Cannot use the "format" option of %s when the "html5" option is disabled.', self::class));
+            }
 
-        $resolver->setAllowedTypes('input_format', 'string');
+            return '';
+        });
     }
 
     /**
diff --git a/src/Symfony/Component/Form/Extension/Core/Type/DateType.php b/src/Symfony/Component/Form/Extension/Core/Type/DateType.php
index ced29d88e0..39002df2b6 100644
--- a/src/Symfony/Component/Form/Extension/Core/Type/DateType.php
+++ b/src/Symfony/Component/Form/Extension/Core/Type/DateType.php
@@ -306,8 +306,16 @@ class DateType extends AbstractType
         $resolver->setAllowedTypes('years', 'array');
         $resolver->setAllowedTypes('months', 'array');
         $resolver->setAllowedTypes('days', 'array');
-
         $resolver->setAllowedTypes('input_format', 'string');
+
+        $resolver->setDeprecated('html5', function (Options $options, $html5) {
+            if ($html5 && 'single_text' === $options['widget'] && self::HTML5_FORMAT !== $options['format']) {
+                return sprintf('Using a custom format when the "html5" option of %s is enabled is deprecated since Symfony 4.3 and will lead to an exception in 5.0.', self::class);
+                //throw new LogicException(sprintf('Cannot use the "format" option of %s when the "html5" option is disabled.', self::class));
+            }
+
+            return '';
+        });
     }
 
     /**
diff --git a/src/Symfony/Component/Form/Tests/Command/DebugCommandTest.php b/src/Symfony/Component/Form/Tests/Command/DebugCommandTest.php
index 99391245da..b572daf7b2 100644
--- a/src/Symfony/Component/Form/Tests/Command/DebugCommandTest.php
+++ b/src/Symfony/Component/Form/Tests/Command/DebugCommandTest.php
@@ -45,7 +45,7 @@ class DebugCommandTest extends TestCase
 Built-in form types (Symfony\Component\Form\Extension\Core\Type)
 ----------------------------------------------------------------
 
- DateTimeType, IntegerType, TimezoneType
+ BirthdayType, DateTimeType, DateType, IntegerType, TimezoneType
 
 Service form types
 ------------------
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTimeTypeTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTimeTypeTest.php
index 20899c1570..93935157fe 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTimeTypeTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTimeTypeTest.php
@@ -470,6 +470,9 @@ class DateTimeTypeTest extends BaseTypeTest
         $this->assertArrayNotHasKey('type', $view->vars);
     }
 
+    /**
+     * @group legacy
+     */
     public function testDontPassHtml5TypeIfNotHtml5Format()
     {
         $view = $this->factory->create(static::TESTED_TYPE, null, [
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTypeTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTypeTest.php
index 3ff363f958..f84547141f 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTypeTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTypeTest.php
@@ -76,6 +76,7 @@ class DateTypeTest extends BaseTypeTest
             'widget' => 'single_text',
             'input' => 'datetime',
             'format' => 'yyyy',
+            'html5' => false,
         ]);
 
         $form->submit('2010');
@@ -93,6 +94,7 @@ class DateTypeTest extends BaseTypeTest
 
         $form = $this->factory->create(static::TESTED_TYPE, null, [
             'format' => \IntlDateFormatter::MEDIUM,
+            'html5' => false,
             'model_timezone' => 'UTC',
             'view_timezone' => 'UTC',
             'widget' => 'single_text',
@@ -114,6 +116,7 @@ class DateTypeTest extends BaseTypeTest
 
         $form = $this->factory->create(static::TESTED_TYPE, null, [
             'format' => \IntlDateFormatter::MEDIUM,
+            'html5' => false,
             'model_timezone' => 'UTC',
             'view_timezone' => 'UTC',
             'widget' => 'single_text',
@@ -136,6 +139,7 @@ class DateTypeTest extends BaseTypeTest
 
         $form = $this->factory->create(static::TESTED_TYPE, null, [
             'format' => \IntlDateFormatter::MEDIUM,
+            'html5' => false,
             'model_timezone' => 'UTC',
             'view_timezone' => 'UTC',
             'widget' => 'single_text',
@@ -157,6 +161,7 @@ class DateTypeTest extends BaseTypeTest
 
         $form = $this->factory->create(static::TESTED_TYPE, null, [
             'format' => \IntlDateFormatter::MEDIUM,
+            'html5' => false,
             'model_timezone' => 'UTC',
             'view_timezone' => 'UTC',
             'widget' => 'single_text',
@@ -180,6 +185,7 @@ class DateTypeTest extends BaseTypeTest
 
         $form = $this->factory->create(static::TESTED_TYPE, null, [
             'format' => \IntlDateFormatter::MEDIUM,
+            'html5' => false,
             'model_timezone' => 'UTC',
             'view_timezone' => 'UTC',
             'widget' => 'single_text',
@@ -270,6 +276,7 @@ class DateTypeTest extends BaseTypeTest
             'model_timezone' => 'UTC',
             'view_timezone' => 'UTC',
             'format' => 'MM*yyyy*dd',
+            'html5' => false,
             'widget' => 'single_text',
             'input' => 'datetime',
         ]);
@@ -286,6 +293,7 @@ class DateTypeTest extends BaseTypeTest
             'model_timezone' => 'UTC',
             'view_timezone' => 'UTC',
             'format' => 'MM*yyyy*dd',
+            'html5' => false,
             'widget' => 'single_text',
             'input' => 'string',
         ]);
@@ -302,6 +310,7 @@ class DateTypeTest extends BaseTypeTest
             'model_timezone' => 'UTC',
             'view_timezone' => 'UTC',
             'format' => 'MM*yyyy*dd',
+            'html5' => false,
             'widget' => 'single_text',
             'input' => 'timestamp',
         ]);
@@ -320,6 +329,7 @@ class DateTypeTest extends BaseTypeTest
             'model_timezone' => 'UTC',
             'view_timezone' => 'UTC',
             'format' => 'MM*yyyy*dd',
+            'html5' => false,
             'widget' => 'single_text',
             'input' => 'array',
         ]);
@@ -368,6 +378,7 @@ class DateTypeTest extends BaseTypeTest
     {
         $this->factory->create(static::TESTED_TYPE, null, [
             'format' => '0',
+            'html5' => false,
             'widget' => 'single_text',
             'input' => 'string',
         ]);
@@ -394,6 +405,7 @@ class DateTypeTest extends BaseTypeTest
         $this->factory->create(static::TESTED_TYPE, null, [
             'widget' => 'single_text',
             'format' => 'wrong',
+            'html5' => false,
         ]);
     }
 
@@ -456,6 +468,7 @@ class DateTypeTest extends BaseTypeTest
 
         $form = $this->factory->create(static::TESTED_TYPE, null, [
             'format' => \IntlDateFormatter::MEDIUM,
+            'html5' => false,
             'model_timezone' => 'UTC',
             'view_timezone' => 'America/New_York',
             'input' => 'string',
@@ -478,6 +491,7 @@ class DateTypeTest extends BaseTypeTest
 
         $form = $this->factory->create(static::TESTED_TYPE, null, [
             'format' => \IntlDateFormatter::MEDIUM,
+            'html5' => false,
             'model_timezone' => 'UTC',
             'view_timezone' => 'America/New_York',
             'input' => 'datetime',
@@ -856,6 +870,7 @@ class DateTypeTest extends BaseTypeTest
         $view = $this->factory->create(static::TESTED_TYPE, null, [
             'widget' => 'single_text',
             'format' => \IntlDateFormatter::MEDIUM,
+            'html5' => false,
         ])
             ->createView();