.../src/Normalizer/MediaEntitiesNormalizer.php     | 37 ++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/core/modules/media/src/Normalizer/MediaEntitiesNormalizer.php b/core/modules/media/src/Normalizer/MediaEntitiesNormalizer.php
new file mode 100644
index 0000000..3fe903f
--- /dev/null
+++ b/core/modules/media/src/Normalizer/MediaEntitiesNormalizer.php
@@ -0,0 +1,37 @@
+<?php
+
+namespace Drupal\media\Normalizer;
+
+use Drupal\media\MediaInterface;
+use Drupal\media\MediaTypeInterface;
+use Drupal\serialization\Normalizer\NormalizerBase;
+use Symfony\Component\Serializer\Exception\UnsupportedException;
+use Symfony\Component\Serializer\Normalizer\DenormalizerInterface;
+
+/**
+ * 'media' and 'media_type' entities do not yet support (de)normalization.
+ *
+ * @todo Remove this in https://www.drupal.org/node/2895573
+ */
+class MediaEntitiesNormalizer extends NormalizerBase implements DenormalizerInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $supportedInterfaceOrClass = [MediaInterface::class, MediaTypeInterface::class];
+
+  /**
+   * {@inheritdoc}
+   */
+  public function normalize($object, $format = null, array $context = array()) {
+    throw new UnsupportedException($object instanceof MediaInterface ? 'Normalizing media entities is not yet supported.' : 'Normalizing media_type entities is not yet supported.');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function denormalize($data, $class, $format = NULL, array $context = []) {
+    throw new UnsupportedException(in_array(MediaInterface::class, class_implements($class), TRUE) ? 'Denormalizing media entities is not yet supported.' : 'Denormalizing media_type entities is not yet supported.');
+  }
+
+}