diff -u b/core/modules/image/src/Controller/QuickEditImageController.php b/core/modules/image/src/Controller/QuickEditImageController.php
--- b/core/modules/image/src/Controller/QuickEditImageController.php
+++ b/core/modules/image/src/Controller/QuickEditImageController.php
@@ -195,9 +195,23 @@
       throw new BadRequestHttpException('Requested Entity is not a Content Entity.');
     }
 
-    // Get the first item (we only support single-cardinality image fields).
-    $field = $entity->getTranslation($langcode)->$field_name->get(0);
+    // Check that this field exists.
+    /** @var \Drupal\Core\Field\FieldItemListInterface $field_list */
+    $field_list = $entity->getTranslation($langcode)->$field_name;
+    if (!$field_list) {
+      throw new BadRequestHttpException('Requested Field does not exist.');
+    }
+
+    // If the list is empty, append an empty item to use.
+    if ($field_list->isEmpty()) {
+      $field = $field_list->appendItem();
+    }
+    // Otherwise, use the first item.
+    else {
+      $field = $entity->getTranslation($langcode)->$field_name->get(0);
+    }
 
+    // Ensure that the field is the type we expect.
     if (!($field instanceof ImageItem)) {
       throw new BadRequestHttpException('Requested Field is not of type "image".');
     }
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/image/src/Tests/QuickEditImageTest.php
@@ -0,0 +1,138 @@
+<?php
+
+namespace Drupal\image\Tests;
+
+/**
+ * Tests the endpoints used by the "image" in-place editor.
+ *
+ * @group image
+ */
+class QuickEditImageTest extends ImageFieldTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = ['node', 'image', 'quickedit'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    // Grant Quick Edit access to the current admin user.
+    $rid = $this->createRole(['access in-place editing']);
+    $this->adminUser->addRole($rid);
+    $this->adminUser->save();
+
+    // Create a field with basic resolution validators.
+    $field_settings = [
+      'max_resolution' => '100x',
+      'min_resolution' => '50x',
+    ];
+    $this->createImageField('image_test', 'article', [], $field_settings);
+  }
+
+  /**
+   * Tests that the field info route returns expected data.
+   */
+  function testFieldInfo() {
+    // Create a test Node.
+    $node = $this->drupalCreateNode([
+      'type' => 'article',
+      'title' => t('Test Node'),
+    ]);
+    $info = $this->drupalGetJSON('quickedit/image/info/node/' . $node->id() . '/image_test/' . $node->language()->getId() . '/default');
+    // Assert that the default settings for our field are respected by our JSON
+    // endpoint.
+    $this->assertTrue($info['alt_field']);
+    $this->assertFalse($info['title_field']);
+  }
+
+  /**
+   * Tests that uploading a valid image works.
+   */
+  function testValidImageUpload() {
+    // Create a test Node.
+    $node = $this->drupalCreateNode([
+      'type' => 'article',
+      'title' => t('Test Node'),
+    ]);
+
+    // We want a test image that is a valid size.
+    $valid_image = FALSE;
+    $image_factory = $this->container->get('image.factory');
+    foreach ($this->drupalGetTestFiles('image') as $image) {
+      $image_file = $image_factory->get($image->uri);
+      if ($image_file->getWidth() > 50 && $image_file->getWidth() < 100) {
+        $valid_image = $image;
+        break;
+      }
+    }
+    $this->uploadImage($valid_image, $node->id(), 'image_test', $node->language()->getId());
+    $this->assertText('fid', t('Valid upload completed successfully.'));
+  }
+
+  /**
+   * Tests that uploading a invalid image does not work.
+   */
+  function testInvalidUpload() {
+    // Create a test Node.
+    $node = $this->drupalCreateNode([
+      'type' => 'article',
+      'title' => t('Test Node'),
+    ]);
+
+    // We want a test image that will fail validation.
+    $invalid_image = FALSE;
+    /** @var \Drupal\Core\Image\ImageFactory $image_factory */
+    $image_factory = $this->container->get('image.factory');
+    foreach ($this->drupalGetTestFiles('image') as $image) {
+      /** @var \Drupal\Core\Image\ImageInterface $image_file */
+      $image_file = $image_factory->get($image->uri);
+      if ($image_file->getWidth() < 50 || $image_file->getWidth() > 100 ) {
+        $invalid_image = $image;
+        break;
+      }
+    }
+    $this->uploadImage($invalid_image, $node->id(), 'image_test', $node->language()->getId());
+    $this->assertText('main_error', t('Invalid upload returned errors.'));
+  }
+
+  /**
+   * Uploads an image using the image module's Quick Edit route.
+   *
+   * @param object $image
+   *   The image to upload.
+   * @param integer $nid
+   *   The target node ID.
+   * @param string $field_name
+   *   The target field machine name.
+   * @param string $langcode
+   *   The langcode to use when setting the field's value.
+   *
+   * @return mixed
+   *   The content returned from the call to $this->curlExec().
+   */
+  function uploadImage($image, $nid, $field_name, $langcode) {
+    $filepath = $this->container->get('file_system')->realpath($image->uri);
+    $data = [
+      'files[image]' => curl_file_create($filepath),
+    ];
+    $path = 'quickedit/image/upload/node/' . $nid . '/' . $field_name . '/' . $langcode . '/default';
+    // We assemble the curl request ourselves as drupalPost cannot process file
+    // uploads, and drupalPostForm only works with typical Drupal forms.
+    return $this->curlExec([
+      CURLOPT_URL => $this->buildUrl($path, []),
+      CURLOPT_POST => TRUE,
+      CURLOPT_POSTFIELDS => $data,
+      CURLOPT_HTTPHEADER => [
+        'Accept: application/json',
+        'Content-Type: multipart/form-data',
+      ],
+    ]);
+  }
+
+}