diff --git a/src/Symfony/Component/Form/Extension/Core/DataMapper/PropertyPathMapper.php b/src/Symfony/Component/Form/Extension/Core/DataMapper/PropertyPathMapper.php
index 657d9d63bec26..ffbd365898152 100644
--- a/src/Symfony/Component/Form/Extension/Core/DataMapper/PropertyPathMapper.php
+++ b/src/Symfony/Component/Form/Extension/Core/DataMapper/PropertyPathMapper.php
@@ -13,6 +13,8 @@
 
 use Symfony\Component\Form\DataMapperInterface;
 use Symfony\Component\Form\Exception\UnexpectedTypeException;
+use Symfony\Component\PropertyAccess\Exception\AccessException;
+use Symfony\Component\PropertyAccess\Exception\UninitializedPropertyException;
 use Symfony\Component\PropertyAccess\PropertyAccess;
 use Symfony\Component\PropertyAccess\PropertyAccessorInterface;
 
@@ -46,7 +48,12 @@ public function mapDataToForms($data, $forms)
             $config = $form->getConfig();
 
             if (!$empty && null !== $propertyPath && $config->getMapped()) {
-                $form->setData($this->propertyAccessor->getValue($data, $propertyPath));
+                try {
+                    $form->setData($this->propertyAccessor->getValue($data, $propertyPath));
+                } catch (AccessException $e) {
+                    // Skip unitialized properties on $data
+                    $this->catchUninitializedPropertyException($e);
+                }
             } else {
                 $form->setData($config->getData());
             }
@@ -76,16 +83,54 @@ public function mapFormsToData($forms, &$data)
                 $propertyValue = $form->getData();
                 // If the field is of type DateTimeInterface and the data is the same skip the update to
                 // keep the original object hash
-                if ($propertyValue instanceof \DateTimeInterface && $propertyValue == $this->propertyAccessor->getValue($data, $propertyPath)) {
+                if ($propertyValue instanceof \DateTimeInterface && $propertyValue == $this->getPropertyValue($data, $propertyPath)) {
                     continue;
                 }
 
                 // If the data is identical to the value in $data, we are
                 // dealing with a reference
-                if (!\is_object($data) || !$config->getByReference() || $propertyValue !== $this->propertyAccessor->getValue($data, $propertyPath)) {
+                if (!\is_object($data) || !$config->getByReference() || $propertyValue !== $this->getPropertyValue($data, $propertyPath)) {
                     $this->propertyAccessor->setValue($data, $propertyPath, $propertyValue);
                 }
             }
         }
     }
+
+    /**
+     * Get the property value per PropertyAccessor.
+     * Treat uninitialized properties as null.
+     *
+     * @param object|array                 $objectOrArray The object or array to traverse
+     * @param string|PropertyPathInterface $propertyPath  The property path to read
+     *
+     * @return mixed The value at the end of the property path
+     *
+     * @throws Exception\InvalidArgumentException If the property path is invalid
+     * @throws Exception\UnexpectedTypeException  If a value within the path is neither object nor array
+     */
+    private function getPropertyValue($data, $propertyPath)
+    {
+        try {
+            return $this->propertyAccessor->getValue($data, $propertyPath);
+        } catch (AccessException $e) {
+            // The following line might be removed in future versions
+            // See https://github.com/symfony/symfony/issues/36754
+            $this->catchUninitializedPropertyException($e);
+
+            return null;
+        }
+    }
+
+    /**
+     * Throw everything but UninitializedPropertyException.
+     */
+    private function catchUninitializedPropertyException(AccessException $e)
+    {
+        if (!$e instanceof UninitializedPropertyException
+            // For versions without UninitializedPropertyException check the exception message
+            && (class_exists(UninitializedPropertyException::class) || false === strpos($e->getMessage(), 'You should initialize it'))
+        ) {
+            throw $e;
+        }
+    }
 }
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/DataMapper/PropertyPathMapperTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/DataMapper/PropertyPathMapperTest.php
index da351295c381e..f98beecb3f229 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/DataMapper/PropertyPathMapperTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/DataMapper/PropertyPathMapperTest.php
@@ -17,6 +17,7 @@
 use Symfony\Component\Form\Extension\Core\DataMapper\PropertyPathMapper;
 use Symfony\Component\Form\Form;
 use Symfony\Component\Form\FormConfigBuilder;
+use Symfony\Component\Form\Tests\Fixtures\TypehintedPropertiesCar;
 use Symfony\Component\PropertyAccess\PropertyAccess;
 use Symfony\Component\PropertyAccess\PropertyAccessorInterface;
 use Symfony\Component\PropertyAccess\PropertyPath;
@@ -113,6 +114,22 @@ public function testMapDataToFormsIgnoresUnmapped()
         $this->assertNull($form->getData());
     }
 
+    /**
+     * @requires PHP 7.4
+     */
+    public function testMapDataToFormsIgnoresUninitializedProperties()
+    {
+        $engineForm = new Form(new FormConfigBuilder('engine', \stdClass::class, $this->dispatcher));
+        $colorForm = new Form(new FormConfigBuilder('color', \stdClass::class, $this->dispatcher));
+
+        $car = new TypehintedPropertiesCar();
+        $car->engine = new \stdClass();
+
+        $this->mapper->mapDataToForms($car, [$engineForm, $colorForm]);
+
+        $this->assertSame($car->engine, $engineForm->getData());
+    }
+
     public function testMapDataToFormsSetsDefaultDataIfPassedDataIsNull()
     {
         $default = new \stdClass();
@@ -293,13 +310,29 @@ public function testMapFormsToDataIgnoresDisabled()
         $config->setPropertyPath($propertyPath);
         $config->setData($engine);
         $config->setDisabled(true);
-        $form = new Form($config);
+        $form = new SubmittedForm($config);
 
         $this->mapper->mapFormsToData([$form], $car);
 
         $this->assertSame($initialEngine, $car->engine);
     }
 
+    /**
+     * @requires PHP 7.4
+     */
+    public function testMapFormsToUninitializedProperties()
+    {
+        $engine = new \stdClass();
+        $car = new TypehintedPropertiesCar();
+        $config = new FormConfigBuilder('engine', \stdClass::class, $this->dispatcher);
+        $config->setData($engine);
+        $form = new SubmittedForm($config);
+
+        $this->mapper->mapFormsToData([$form], $car);
+
+        $this->assertSame($engine, $car->engine);
+    }
+
     /**
      * @dataProvider provideDate
      */
@@ -339,7 +372,7 @@ public function isSubmitted()
     }
 }
 
-class NotSynchronizedForm extends Form
+class NotSynchronizedForm extends SubmittedForm
 {
     public function isSynchronized()
     {
diff --git a/src/Symfony/Component/Form/Tests/Fixtures/TypehintedPropertiesCar.php b/src/Symfony/Component/Form/Tests/Fixtures/TypehintedPropertiesCar.php
new file mode 100644
index 0000000000000..df1ebe2c9bf1f
--- /dev/null
+++ b/src/Symfony/Component/Form/Tests/Fixtures/TypehintedPropertiesCar.php
@@ -0,0 +1,8 @@
+<?php
+namespace Symfony\Component\Form\Tests\Fixtures;
+
+class TypehintedPropertiesCar
+{
+    public ?\stdClass $engine;
+    public ?\stdClass $color;
+}