diff --git a/src/Serializer/AbstractItemNormalizer.php b/src/Serializer/AbstractItemNormalizer.php
index 80b31b0a3fd..48dd5f46b75 100644
--- a/src/Serializer/AbstractItemNormalizer.php
+++ b/src/Serializer/AbstractItemNormalizer.php
@@ -315,7 +315,13 @@ protected function denormalizeRelation(string $attributeName, PropertyMetadata $
             // repeat the code so that IRIs keep working with the json format
             if (true === $this->allowPlainIdentifiers && $this->itemDataProvider) {
                 try {
-                    return $this->itemDataProvider->getItem($className, $value, null, $context + ['fetch_data' => true]);
+                    $item = $this->itemDataProvider->getItem($className, $value, null, $context + ['fetch_data' => true]);
+
+                    if (null === $item) {
+                        throw new ItemNotFoundException(sprintf('Item with id "%s" not found for class "%s".', $value, $className));
+                    }
+
+                    return $item;
                 } catch (ItemNotFoundException $e) {
                     throw new InvalidArgumentException($e->getMessage(), $e->getCode(), $e);
                 } catch (InvalidArgumentException $e) {
diff --git a/tests/Serializer/AbstractItemNormalizerTest.php b/tests/Serializer/AbstractItemNormalizerTest.php
index 2207508687f..8a2fc7bea41 100644
--- a/tests/Serializer/AbstractItemNormalizerTest.php
+++ b/tests/Serializer/AbstractItemNormalizerTest.php
@@ -17,6 +17,7 @@
 use ApiPlatform\Core\Api\ResourceClassResolverInterface;
 use ApiPlatform\Core\DataProvider\ItemDataProviderInterface;
 use ApiPlatform\Core\Exception\InvalidArgumentException;
+use ApiPlatform\Core\Exception\ItemNotFoundException;
 use ApiPlatform\Core\Metadata\Property\Factory\PropertyMetadataFactoryInterface;
 use ApiPlatform\Core\Metadata\Property\Factory\PropertyNameCollectionFactoryInterface;
 use ApiPlatform\Core\Metadata\Property\PropertyMetadata;
@@ -287,6 +288,73 @@ public function testDenormalize()
         ], Dummy::class);
     }
 
+    /**
+     * @expectedException \ApiPlatform\Core\Exception\InvalidArgumentException
+     * @expectedExceptionMessage NotFound exception
+     */
+    public function testDenormalizeNotFound()
+    {
+        $propertyNameCollectionFactoryProphecy = $this->prophesize(PropertyNameCollectionFactoryInterface::class);
+        $propertyNameCollectionFactoryProphecy->create(Dummy::class, [])->willReturn(
+            new PropertyNameCollection(['name', 'relatedDummy', 'relatedDummies'])
+        )->shouldBeCalled();
+
+        $propertyMetadataFactoryProphecy = $this->prophesize(PropertyMetadataFactoryInterface::class);
+        $propertyMetadataFactoryProphecy->create(Dummy::class, 'name', [])->willReturn(
+            new PropertyMetadata(new Type(Type::BUILTIN_TYPE_STRING), '', false, true)
+        )->shouldBeCalled();
+        $propertyMetadataFactoryProphecy->create(Dummy::class, 'relatedDummy', [])->willReturn(
+            new PropertyMetadata(
+                new Type(Type::BUILTIN_TYPE_OBJECT, false, RelatedDummy::class),
+                '',
+                false,
+                true,
+                false,
+                false
+            )
+        )->shouldBeCalled();
+        $propertyMetadataFactoryProphecy->create(Dummy::class, 'relatedDummies', [])->willReturn(
+            new PropertyMetadata(
+                new Type(Type::BUILTIN_TYPE_OBJECT,
+                    false,
+                    ArrayCollection::class,
+                    true,
+                    new Type(Type::BUILTIN_TYPE_INT),
+                    new Type(Type::BUILTIN_TYPE_OBJECT, false, RelatedDummy::class)
+                ),
+                '',
+                false,
+                true,
+                false,
+                false
+            )
+        )->shouldBeCalled();
+
+        $iriConverterProphecy = $this->prophesize(IriConverterInterface::class);
+        $iriConverterProphecy->getItemFromIri('/dummies/1', Argument::type('array'))->willThrow(new ItemNotFoundException('NotFound exception'))->shouldBeCalled();
+
+        $propertyAccessorProphecy = $this->prophesize(PropertyAccessorInterface::class);
+
+        $resourceClassResolverProphecy = $this->prophesize(ResourceClassResolverInterface::class);
+
+        $serializerProphecy = $this->prophesize(SerializerInterface::class);
+        $serializerProphecy->willImplement(NormalizerInterface::class);
+
+        $normalizer = $this->getMockForAbstractClass(AbstractItemNormalizer::class, [
+            $propertyNameCollectionFactoryProphecy->reveal(),
+            $propertyMetadataFactoryProphecy->reveal(),
+            $iriConverterProphecy->reveal(),
+            $resourceClassResolverProphecy->reveal(),
+            $propertyAccessorProphecy->reveal(),
+        ]);
+        $normalizer->setSerializer($serializerProphecy->reveal());
+
+        $normalizer->denormalize([
+            'name' => 'foo',
+            'relatedDummy' => '/dummies/1',
+        ], Dummy::class);
+    }
+
     public function testDenormalizeWritableLinks()
     {
         $relatedDummy1 = new RelatedDummy();
@@ -676,7 +744,58 @@ public function testDenormalizeRelationWithPlainId()
         $serializerProphecy->willImplement(DenormalizerInterface::class);
 
         $itemDataProviderProphecy = $this->prophesize(ItemDataProviderInterface::class);
-        $itemDataProviderProphecy->getItem(RelatedDummy::class, 1, null, Argument::type('array'))->shouldBeCalled();
+        $itemDataProviderProphecy->getItem(RelatedDummy::class, 1, null, Argument::type('array'))->willReturn(new RelatedDummy())->shouldBeCalled();
+
+        $normalizer = $this->getMockForAbstractClass(AbstractItemNormalizer::class, [
+            $propertyNameCollectionFactoryProphecy->reveal(),
+            $propertyMetadataFactoryProphecy->reveal(),
+            $iriConverterProphecy->reveal(),
+            $resourceClassResolverProphecy->reveal(),
+            $propertyAccessorProphecy->reveal(),
+            null,
+            null,
+            $itemDataProviderProphecy->reveal(),
+            true,
+        ]);
+        $normalizer->setSerializer($serializerProphecy->reveal());
+
+        $normalizer->denormalize(['relatedDummy' => 1], Dummy::class, 'jsonld');
+    }
+
+    /**
+     * @expectedException \ApiPlatform\Core\Exception\InvalidArgumentException
+     * @expectedExceptionMessage Item with id "1" not found for class "ApiPlatform\Core\Tests\Fixtures\TestBundle\Entity\RelatedDummy".
+     */
+    public function testDenormalizeNotFoundRelationWithPlainId()
+    {
+        $propertyNameCollectionFactoryProphecy = $this->prophesize(PropertyNameCollectionFactoryInterface::class);
+        $propertyNameCollectionFactoryProphecy->create(Dummy::class, [])->willReturn(
+            new PropertyNameCollection(['relatedDummy'])
+        )->shouldBeCalled();
+
+        $propertyMetadataFactoryProphecy = $this->prophesize(PropertyMetadataFactoryInterface::class);
+        $propertyMetadataFactoryProphecy->create(Dummy::class, 'relatedDummy', [])->willReturn(
+            new PropertyMetadata(
+                new Type(Type::BUILTIN_TYPE_OBJECT, false, RelatedDummy::class),
+                '',
+                false,
+                true,
+                false,
+                false
+            )
+        )->shouldBeCalled();
+
+        $iriConverterProphecy = $this->prophesize(IriConverterInterface::class);
+        $propertyAccessorProphecy = $this->prophesize(PropertyAccessorInterface::class);
+
+        $resourceClassResolverProphecy = $this->prophesize(ResourceClassResolverInterface::class);
+        $resourceClassResolverProphecy->isResourceClass(RelatedDummy::class)->willReturn(true)->shouldBeCalled();
+
+        $serializerProphecy = $this->prophesize(SerializerInterface::class);
+        $serializerProphecy->willImplement(DenormalizerInterface::class);
+
+        $itemDataProviderProphecy = $this->prophesize(ItemDataProviderInterface::class);
+        $itemDataProviderProphecy->getItem(RelatedDummy::class, 1, null, Argument::type('array'))->willReturn(null)->shouldBeCalled();
 
         $normalizer = $this->getMockForAbstractClass(AbstractItemNormalizer::class, [
             $propertyNameCollectionFactoryProphecy->reveal(),