diff -u b/core/modules/media/src/Entity/MediaType.php b/core/modules/media/src/Entity/MediaType.php
--- b/core/modules/media/src/Entity/MediaType.php
+++ b/core/modules/media/src/Entity/MediaType.php
@@ -3,13 +3,10 @@
 namespace Drupal\media\Entity;
 
 use Drupal\Core\Config\Entity\ConfigEntityBundleBase;
-use Drupal\Core\Entity\EntityStorageInterface;
 use Drupal\Core\Entity\EntityWithPluginCollectionInterface;
 use Drupal\Core\Plugin\DefaultSingleLazyPluginCollection;
-use Drupal\field\FieldStorageConfigInterface;
 use Drupal\media\MediaTypeInterface;
 use Drupal\media\MediaInterface;
-use Drupal\media\SourceFieldInterface;
 
 /**
  * Defines the Media type configuration entity.
@@ -225,68 +222,6 @@
   /**
    * {@inheritdoc}
    */
-  public function preSave(EntityStorageInterface $storage) {
-    // If the handler uses a source field, we'll need to store its name before
-    // saving. We'd need to double-save if we did this in postSave().
-    $handler = $this->getHandler();
-    if ($handler instanceof SourceFieldInterface) {
-      $field_storage = $handler->getSourceField($this)->getFieldStorageDefinition();
-      // If the field storage is a new (unsaved) config entity, save it.
-      if ($field_storage instanceof FieldStorageConfigInterface && $field_storage->isNew()) {
-        $field_storage->save();
-      }
-    }
-
-    parent::preSave($storage);
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function postSave(EntityStorageInterface $storage, $update = TRUE) {
-    parent::postSave($storage, $update);
-
-    // If the handler is using a source field, we may need to save it if it's
-    // new. The field storage is guaranteed to exist already because preSave()
-    // took care of that.
-    $handler = $this->getHandler();
-    if ($handler instanceof SourceFieldInterface) {
-      $field = $handler->getSourceField($this);
-
-      // If the field is new, save it and add it to this bundle's view and form
-      // displays.
-      if ($field->isNew()) {
-        // Ensure the field is saved correctly before adding it to the displays.
-        $field->save();
-
-        $entity_type = $field->getTargetEntityTypeId();
-        $bundle = $field->getTargetBundle();
-
-        if ($field->isDisplayConfigurable('form')) {
-          // Use the default widget and settings.
-          $component = \Drupal::service('plugin.manager.field.widget')
-            ->prepareConfiguration($field->getType(), []);
-
-          entity_get_form_display($entity_type, $bundle, 'default')
-            ->setComponent($field->getName(), $component)
-            ->save();
-        }
-        if ($field->isDisplayConfigurable('view')) {
-          // Use the default formatter and settings.
-          $component = \Drupal::service('plugin.manager.field.formatter')
-            ->prepareConfiguration($field->getType(), []);
-
-          entity_get_display($entity_type, $bundle, 'default')
-            ->setComponent($field->getName(), $component)
-            ->save();
-        }
-      }
-    }
-  }
-
-  /**
-   * {@inheritdoc}
-   */
   public function getFieldMap() {
     return $this->field_map;
   }
diff -u b/core/modules/media/src/MediaHandlerBase.php b/core/modules/media/src/MediaHandlerBase.php
--- b/core/modules/media/src/MediaHandlerBase.php
+++ b/core/modules/media/src/MediaHandlerBase.php
@@ -10,6 +10,7 @@
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Plugin\PluginBase;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\field\FieldStorageConfigInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
@@ -218,7 +219,7 @@
   /**
    * {@inheritdoc}
    */
-  public function getSourceField(MediaTypeInterface $type, $retry = TRUE) {
+  public function getSourceField(MediaTypeInterface $type) {
     // If we don't know the name of the source field, we definitely need to
     // create it.
     if (empty($this->configuration['source_field'])) {
@@ -241,9 +242,7 @@
     // If we don't know the name of the source field, we definitely need to
     // create its storage.
     if (empty($this->configuration['source_field'])) {
-      $storage = $this->createSourceFieldStorage();
-      $this->configuration['source_field'] = $storage->getName();
-      return $storage;
+      return $this->createSourceFieldStorage();
     }
     // Even if we do know the name of the source field, we cannot guarantee that
     // its storage exists. So check for the storage and create it if needed.
@@ -262,11 +261,13 @@
    *   The unsaved field storage definition.
    */
   protected function createSourceFieldStorage() {
+    $this->configuration['source_field'] = $this->getSourceFieldName();
+
     return $this->entityTypeManager
       ->getStorage('field_storage_config')
       ->create([
         'entity_type' => 'media',
-        'field_name' => $this->getSourceFieldName(),
+        'field_name' => $this->configuration['source_field'],
         'type' => reset($this->pluginDefinition['allowed_field_types']),
         'locked' => TRUE,
       ]);
diff -u b/core/modules/media/src/MediaTypeForm.php b/core/modules/media/src/MediaTypeForm.php
--- b/core/modules/media/src/MediaTypeForm.php
+++ b/core/modules/media/src/MediaTypeForm.php
@@ -9,6 +9,7 @@
 use Drupal\Core\Field\BaseFieldDefinition;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Form\SubformState;
+use Drupal\field\FieldStorageConfigInterface;
 use Drupal\media\Entity\MediaType;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
@@ -262,10 +263,9 @@
    *   Sub-form state for the handler configuration form.
    */
   protected function getHandlerSubFormState(array $form, FormStateInterface $form_state) {
-    $subform_state = SubformState::createForSubform($form['handler_dependent']['handler_configuration'], $form, $form_state);
-    $subform_state->set('operation', $this->operation);
-    $subform_state->set('type', $this->entity);
-    return $subform_state;
+    return SubformState::createForSubform($form['handler_dependent']['handler_configuration'], $form, $form_state)
+      ->set('operation', $this->operation)
+      ->set('type', $this->entity);
   }
 
   /**
@@ -318,9 +318,55 @@
    * {@inheritdoc}
    */
   public function save(array $form, FormStateInterface $form_state) {
-    $status = parent::save($form, $form_state);
     $bundle = $this->entity;
 
+    // If the handler uses a source field, we'll need to store its name before
+    // saving. We'd need to double-save if we did this in postSave().
+    $handler = $bundle->getHandler();
+    if ($handler instanceof SourceFieldInterface) {
+      $field = $handler->getSourceField($bundle);
+      $status = parent::save($form, $form_state);
+
+      $field_storage = $field->getFieldStorageDefinition();
+      // If the field storage is a new (unsaved) config entity, save it.
+      if ($field_storage instanceof FieldStorageConfigInterface && $field_storage->isNew()) {
+        $field_storage->save();
+      }
+
+      // If the field is new, save it and add it to this bundle's view and form
+      // displays.
+      if ($field->isNew()) {
+        // Ensure the field is saved correctly before adding it to the displays.
+        $field->save();
+
+        $entity_type = $field->getTargetEntityTypeId();
+        $targetBundle = $field->getTargetBundle();
+
+        if ($field->isDisplayConfigurable('form')) {
+          // Use the default widget and settings.
+          $component = \Drupal::service('plugin.manager.field.widget')
+            ->prepareConfiguration($field->getType(), []);
+
+          entity_get_form_display($entity_type, $targetBundle, 'default')
+            ->setComponent($field->getName(), $component)
+            ->save();
+        }
+        if ($field->isDisplayConfigurable('view')) {
+          // Use the default formatter and settings.
+          $component = \Drupal::service('plugin.manager.field.formatter')
+            ->prepareConfiguration($field->getType(), []);
+
+          entity_get_display($entity_type, $targetBundle, 'default')
+            ->setComponent($field->getName(), $component)
+            ->save();
+        }
+      }
+    } else {
+      $status = parent::save($form, $form_state);
+    }
+
+
+
     $t_args = ['%name' => $bundle->label()];
     if ($status == SAVED_UPDATED) {
       drupal_set_message($this->t('The media type %name has been updated.', $t_args));
diff -u b/core/modules/media/tests/src/FunctionalJavascript/MediaJavascriptTestBase.php b/core/modules/media/tests/src/FunctionalJavascript/MediaJavascriptTestBase.php
--- b/core/modules/media/tests/src/FunctionalJavascript/MediaJavascriptTestBase.php
+++ b/core/modules/media/tests/src/FunctionalJavascript/MediaJavascriptTestBase.php
@@ -12,10 +12,6 @@
  */
 abstract class MediaJavascriptTestBase extends JavascriptTestBase {
 
-  use MediaFunctionalTestTrait {
-    createMediaType as drupalCreateMediaType;
-  }
-
   /**
    * Modules to enable.
    *
@@ -111,2 +107,42 @@
 
+  /**
+   * Creates a media type over the UI.
+   *
+   * @param array $values
+   *   The media type values.
+   * @param string $handler
+   *   (optional) The handler plugin that is responsible for additional logic
+   *   related to this media type.
+   *
+   * @return \Drupal\media\MediaTypeInterface
+   *   A newly created media type.
+   */
+  protected function createMediaTypeViaUi(array $values = [], $handler = 'test') {
+    if (!isset($values['bundle'])) {
+      $id = strtolower($this->randomMachineName());
+    }
+    else {
+      $id = $values['bundle'];
+    }
+
+    $session = $this->getSession();
+    $page = $session->getPage();
+
+    $this->drupalGet('admin/structure/media/add');
+    $page->fillField('label', $id);
+    $machine_name = strtolower($id);
+    $this->assertJsCondition("jQuery('.machine-name-value').html() == '$machine_name'");
+    $page->selectFieldOption('handler', $handler);
+    $this->assertSession()->assertWaitOnAjaxRequest();
+
+    $page->pressButton('Save');
+
+    $assert_session = $this->assertSession();
+    $assert_session->pageTextContains('The media type ' . $id . ' has been added.');
+
+
+    return $this->container->get('entity_type.manager')
+      ->getStorage('media_type')
+      ->load($machine_name);
+  }
 }
diff -u b/core/modules/media/tests/src/FunctionalJavascript/MediaUiJavascriptTest.php b/core/modules/media/tests/src/FunctionalJavascript/MediaUiJavascriptTest.php
--- b/core/modules/media/tests/src/FunctionalJavascript/MediaUiJavascriptTest.php
+++ b/core/modules/media/tests/src/FunctionalJavascript/MediaUiJavascriptTest.php
@@ -165,7 +165,7 @@
     $assert_session->pageTextContains('The media type ' . $new_name . ' has been deleted.');
 
     // Test bundle delete prevention when there is existing media.
-    $bundle2 = $this->drupalCreateMediaType();
+    $bundle2 = $this->createMediaTypeViaUi();
     $label2 = $bundle2->label();
     $media = Media::create(['name' => 'lorem ipsum', 'bundle' => $bundle2->id()]);
     $media->save();
diff -u b/core/modules/media/tests/src/Kernel/BasicCreationTest.php b/core/modules/media/tests/src/Kernel/BasicCreationTest.php
--- b/core/modules/media/tests/src/Kernel/BasicCreationTest.php
+++ b/core/modules/media/tests/src/Kernel/BasicCreationTest.php
@@ -76,7 +76,7 @@
     $this->assertEquals('Test type', $test_bundle->get('label'), 'Could not assure the correct type name.');
     $this->assertEquals('Test type.', $test_bundle->get('description'), 'Could not assure the correct type description.');
     $this->assertEquals('test', $test_bundle->get('handler'), 'Could not assure the correct handler.');
-    $this->assertEquals(['source_field' => 'field_media_test_1', 'test_config_value' => 'Kakec'], $test_bundle->get('handler_configuration'), 'Could not assure the correct handler configuration.');
+    $this->assertEquals(['source_field' => '', 'test_config_value' => 'Kakec'], $test_bundle->get('handler_configuration'), 'Could not assure the correct handler configuration.');
     $this->assertEquals([], $test_bundle->get('field_map'), 'Could not assure the correct field map.');
   }
 
@@ -112,14 +112,17 @@
    */
   public function testProgrammaticBundleManipulation() {
     // Creating a bundle programmatically without specifying a source field
-    // should create one automagically.
+    // should create one but it has to be saved programmatically too.
     /** @var FieldConfig $field */
     $field = $this->testBundle->getHandler()->getSourceField($this->testBundle);
     $this->assertInstanceOf(FieldConfig::class, $field);
     $this->assertEquals('field_media_test', $field->getName());
+    $field->getFieldStorageDefinition()->save();
+    $field->save();
     $this->assertFalse($field->isNew());
 
-    // Saving with a non-existent source field should create it.
+    // Saving with a non-existent source field should create one but it has to
+    // be saved programmatically.
     $this->testBundle->getHandler()->setConfiguration([
       'source_field' => 'field_magick',
     ]);
@@ -127,7 +130,7 @@
     $field = $this->testBundle->getHandler()->getSourceField($this->testBundle);
     $this->assertInstanceOf(FieldConfig::class, $field);
     $this->assertEquals('field_magick', $field->getName());
-    $this->assertFalse($field->isNew());
+    $this->assertTrue($field->isNew());
 
     // Trying to save without a source field should create a new, de-duped one.
     $this->testBundle->getHandler()->setConfiguration([]);
@@ -135,6 +138,8 @@
     $field = $this->testBundle->getHandler()->getSourceField($this->testBundle);
     $this->assertInstanceOf(FieldConfig::class, $field);
     $this->assertEquals('field_media_test_1', $field->getName());
+    $field->getFieldStorageDefinition()->save();
+    $field->save();
     $this->assertFalse($field->isNew());
 
     // Trying to reuse an existing field should, well, reuse the existing field.
@@ -145,6 +150,8 @@
     $field = $this->testBundle->getHandler()->getSourceField($this->testBundle);
     $this->assertInstanceOf(FieldConfig::class, $field);
     $this->assertEquals('field_magick', $field->getName());
+    $field->getFieldStorageDefinition()->save();
+    $field->save();
     $this->assertFalse($field->isNew());
     // No new de-duped fields should have been created.
     $duplicates = FieldConfig::loadMultiple([