diff --git a/core/modules/file/file.module b/core/modules/file/file.module
index 9d1592de3e8a0ae0f0b781065eecb50a78a2d0e5..9f0074f7e8ba692e5ab4a067197a3f6ae30385e2 100644
--- a/core/modules/file/file.module
+++ b/core/modules/file/file.module
@@ -850,18 +850,18 @@ function file_save_upload($form_field_name, $validators = array(), $destination
 
     // Check for errors.
     if (!empty($errors)) {
-      $message = t('The specified file %name could not be uploaded.', array('%name' => $file->getFilename()));
-      if (count($errors) > 1) {
-        $item_list = array(
+      $message = array(
+        'error' => array(
+          '#markup' => t('The specified file %name could not be uploaded.', array('%name' => $file->getFilename())),
+        ),
+        'item_list' => array(
           '#theme' => 'item_list',
           '#items' => $errors,
-        );
-        $message = SafeMarkup::set($message . drupal_render($item_list));
-      }
-      else {
-        $message = SafeMarkup::set($message . ' ' . SafeMarkup::escape(array_pop($errors)));
-      }
-      drupal_set_message($message, 'error');
+        ),
+      );
+      // @todo Add support for render arrays in drupal_set_message()? See
+      //  https://www.drupal.org/node/2505497.
+      drupal_set_message(\Drupal::service('renderer')->render($message), 'error');
       $files[$i] = FALSE;
       continue;
     }
diff --git a/core/modules/image/src/Tests/ImageFieldDefaultImagesTest.php b/core/modules/image/src/Tests/ImageFieldDefaultImagesTest.php
index 39e0d50d96fed7d3132b6dc2613ef5677329a991..9dea3f5a9a0247a62f1b0e79c40b2183573933ba 100644
--- a/core/modules/image/src/Tests/ImageFieldDefaultImagesTest.php
+++ b/core/modules/image/src/Tests/ImageFieldDefaultImagesTest.php
@@ -298,7 +298,8 @@ public function testDefaultImages() {
 
     $non_image = $this->drupalGetTestFiles('text');
     $this->drupalPostForm(NULL, array('files[settings_default_image_uuid]' => drupal_realpath($non_image[0]->uri)), t("Upload"));
-    $this->assertText(t('The specified file text-0.txt could not be uploaded. Only files with the following extensions are allowed: png gif jpg jpeg.'), 'Non-image file cannot be used as default image.');
+    $this->assertText('The specified file text-0.txt could not be uploaded.');
+    $this->assertText('Only files with the following extensions are allowed: png gif jpg jpeg.');
 
     // Confirm the default image is shown on the node form.
     $file = File::load($default_images['field_new']->id());
diff --git a/core/modules/image/src/Tests/ImageFieldValidateTest.php b/core/modules/image/src/Tests/ImageFieldValidateTest.php
index 938176a1d0c98c91cb79b79f1c76811eb8e2a313..3822df67ae85155ca8f48f9b463dc4b4c5285653 100644
--- a/core/modules/image/src/Tests/ImageFieldValidateTest.php
+++ b/core/modules/image/src/Tests/ImageFieldValidateTest.php
@@ -45,9 +45,10 @@ function testResolution() {
       }
     }
     $this->uploadNodeImage($image_that_is_too_small, $field_name, 'article');
-    $this->assertRaw(t('The specified file %name could not be uploaded.', array('%name' => $image_that_is_too_small->filename)) . ' ' . t('The image is too small; the minimum dimensions are %dimensions pixels.', array('%dimensions' => '50x50')), 'Node save failed when minimum image resolution was not met.');
+    $this->assertRaw(t('The specified file %name could not be uploaded.', array('%name' => $image_that_is_too_small->filename)));
+    $this->assertRaw(t('The image is too small; the minimum dimensions are %dimensions pixels.', array('%dimensions' => '50x50')));
     $this->uploadNodeImage($image_that_is_too_big, $field_name, 'article');
-    $this->assertText(t('The image was resized to fit within the maximum allowed dimensions of 100x100 pixels.'), 'Image exceeding max resolution was properly resized.');
+    $this->assertText(t('The image was resized to fit within the maximum allowed dimensions of 100x100 pixels.'));
   }
 
   /**