diff --git a/core/modules/datetime_range/src/Plugin/Validation/Constraint/DateRangeFormatConstraint.php b/core/modules/datetime_range/src/Plugin/Validation/Constraint/DateRangeFormatConstraint.php
index 5ad78de..ecfe31c 100644
--- a/core/modules/datetime_range/src/Plugin/Validation/Constraint/DateRangeFormatConstraint.php
+++ b/core/modules/datetime_range/src/Plugin/Validation/Constraint/DateRangeFormatConstraint.php
@@ -19,41 +19,41 @@ class DateRangeFormatConstraint extends Constraint {
    *
    * @var string
    */
-  public $badStartType = "The daterange start value must be a string.";
+  public $badStartType = "The date range start value must be a string.";
 
   /**
    * Message for when the end value isn't a string.
    *
    * @var string
    */
-  public $badEndType = "The daterange end value must be a string.";
+  public $badEndType = "The date range end value must be a string.";
 
   /**
    * Message for when the start value isn't in the proper format.
    *
    * @var string
    */
-  public $badStartFormat = "The daterange start value '@value' is invalid for the format '@format'";
+  public $badStartFormat = "The date range start value '@value' is invalid for the format '@format'";
 
   /**
    * Message for when the end value isn't in the proper format.
    *
    * @var string
    */
-  public $badEndFormat = "The daterange end value '@end_value' is invalid for the format '@format'";
+  public $badEndFormat = "The date range end value '@end_value' is invalid for the format '@format'";
 
   /**
    * Message for when the start value did not parse properly.
    *
    * @var string
    */
-  public $badStartValue = "The daterange start value '@value' did not parse properly for the format '@format'";
+  public $badStartValue = "The date range start value '@value' did not parse properly for the format '@format'";
 
   /**
    * Message for when the end value did not parse properly.
    *
    * @var string
    */
-  public $badEndValue = "The daterange end value '@end_value' did not parse properly for the format '@format'";
+  public $badEndValue = "The date range end value '@end_value' did not parse properly for the format '@format'";
 
 }
diff --git a/core/modules/datetime_range/src/Plugin/Validation/Constraint/DateRangeFormatConstraintValidator.php b/core/modules/datetime_range/src/Plugin/Validation/Constraint/DateRangeFormatConstraintValidator.php
index 752a7d6..6f68280 100644
--- a/core/modules/datetime_range/src/Plugin/Validation/Constraint/DateRangeFormatConstraintValidator.php
+++ b/core/modules/datetime_range/src/Plugin/Validation/Constraint/DateRangeFormatConstraintValidator.php
@@ -34,9 +34,6 @@ public function validate($item, Constraint $constraint) {
 
       if ($stop) return;
 
-      // @todo Reorder this w/ $stop...
-      return;
-
       $datetime_type = $item->getFieldDefinition()->getSetting('datetime_type');
       $format = $datetime_type === DateRangeItem::DATETIME_TYPE_DATE ? DateTimeItemInterface::DATE_STORAGE_FORMAT : DateTimeItemInterface::DATETIME_STORAGE_FORMAT;
 
@@ -49,20 +46,14 @@ public function validate($item, Constraint $constraint) {
           '@value' => $value,
           '@format' => $format,
         ]);
-        return;
+        $stop = TRUE;
       }
       catch (\UnexpectedValueException $e) {
         $this->context->addViolation($constraint->badStartValue, [
           '@value' => $value,
           '@format' => $format,
         ]);
-        return;
-      }
-      if ($start_date === NULL || $start_date->hasErrors()) {
-        $this->context->addViolation($constraint->badStartFormat, [
-          '@value' => $value,
-          '@format' => $format,
-        ]);
+        $stop = TRUE;
       }
 
       $end_date = NULL;
@@ -74,15 +65,25 @@ public function validate($item, Constraint $constraint) {
           '@end_value' => $end_value,
           '@format' => $format,
         ]);
-        return;
+        $stop = TRUE;
       }
       catch (\UnexpectedValueException $e) {
         $this->context->addViolation($constraint->badEndValue, [
           '@end_value' => $end_value,
           '@format' => $format,
         ]);
-        return;
+        $stop = TRUE;
       }
+
+      if ($stop) return;
+
+      if ($start_date === NULL || $start_date->hasErrors()) {
+        $this->context->addViolation($constraint->badStartFormat, [
+          '@value' => $value,
+          '@format' => $format,
+        ]);
+      }
+
       if ($end_date === NULL || $end_date->hasErrors()) {
         $this->context->addViolation($constraint->badEndFormat, [
           '@end_value' => $end_value,
diff --git a/core/modules/datetime_range/src/Plugin/Validation/Constraint/DateRangeStartEndConstraint.php b/core/modules/datetime_range/src/Plugin/Validation/Constraint/DateRangeStartEndConstraint.php
index fb46363..bebdc27 100644
--- a/core/modules/datetime_range/src/Plugin/Validation/Constraint/DateRangeStartEndConstraint.php
+++ b/core/modules/datetime_range/src/Plugin/Validation/Constraint/DateRangeStartEndConstraint.php
@@ -19,6 +19,6 @@ class DateRangeStartEndConstraint extends Constraint {
    *
    * @var string
    */
-  public $badStartEnd = "The daterange end value '@end_value' must equal to or after the start value '@value'";
+  public $badStartEnd = "The date range end value '@end_value' must equal to or after the start value '@value'";
 
 }
diff --git a/core/modules/datetime_range/src/Plugin/Validation/Constraint/DateRangeStartEndConstraintValidator.php b/core/modules/datetime_range/src/Plugin/Validation/Constraint/DateRangeStartEndConstraintValidator.php
index 5a76393..a1d2ea9 100644
--- a/core/modules/datetime_range/src/Plugin/Validation/Constraint/DateRangeStartEndConstraintValidator.php
+++ b/core/modules/datetime_range/src/Plugin/Validation/Constraint/DateRangeStartEndConstraintValidator.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\datetime_range\Plugin\Validation\Constraint;
 
+use Drupal\Core\Datetime\DrupalDateTime;
 use Symfony\Component\Validator\Constraint;
 use Symfony\Component\Validator\ConstraintValidator;
 
@@ -16,14 +17,24 @@ class DateRangeStartEndConstraintValidator extends ConstraintValidator {
   public function validate($item, Constraint $constraint) {
     /* @var $item \Drupal\datetime_range\Plugin\Field\FieldType\DateRangeItem */
     if (isset($item)) {
-      $value = $item->getValue()['value'];
-      $end_value = $item->getValue()['end_value'];
+      $values = $item->getValue();
+      $value = $values['value'];
+      $end_value = $values['end_value'];
 
-      if ($end_value < $value) {
-        $this->context->addViolation($constraint->badStartEnd, [
-          '@value' => $value,
-          '@end_value' => $end_value,
-        ]);
+      // Only run this validation when the item has proper start and end date
+      // objects, which means the values were parsed properly.
+      if (isset($values['start_date']) && $values['start_date'] instanceof DrupalDateTime && isset($values['end_date']) && $values['end_date'] instanceof DrupalDateTime) {
+        /** @var \Drupal\Core\Datetime\DrupalDateTime $start_date */
+        $start_date = $values['start_date'];
+        /** @var \Drupal\Core\Datetime\DrupalDateTime $start_date */
+        $end_date = $values['end_date'];
+
+        if ($start_date->format('c') < $end_date->format('c')) {
+          $this->context->addViolation($constraint->badStartEnd, [
+            '@value' => $value,
+            '@end_value' => $end_value,
+          ]);
+        }
       }
     }
   }
diff --git a/core/modules/datetime_range/tests/src/Functional/EntityResource/EntityTest/EntityTestDatetimeTest.php b/core/modules/datetime_range/tests/src/Functional/EntityResource/EntityTest/EntityTestDaterangeTest.php
similarity index 62%
rename from core/modules/datetime_range/tests/src/Functional/EntityResource/EntityTest/EntityTestDatetimeTest.php
rename to core/modules/datetime_range/tests/src/Functional/EntityResource/EntityTest/EntityTestDaterangeTest.php
index e05895b..49baf9c 100644
--- a/core/modules/datetime_range/tests/src/Functional/EntityResource/EntityTest/EntityTestDatetimeTest.php
+++ b/core/modules/datetime_range/tests/src/Functional/EntityResource/EntityTest/EntityTestDaterangeTest.php
@@ -17,7 +17,7 @@
  *
  * @group datetime
  */
-class EntityTestDatetimeTest extends EntityTestResourceTestBase {
+class EntityTestDaterangeTest extends EntityTestResourceTestBase {
 
   use AnonResourceTestTrait;
 
@@ -36,13 +36,18 @@ class EntityTestDatetimeTest extends EntityTestResourceTestBase {
   protected static $endDateString = '2017-03-02T20:02:00';
 
   /**
-   * Datetime test field name.
+   * Daterange test field name.
    *
    * @var string
    */
   protected static $fieldName = 'field_daterange';
 
   /**
+   * Daterange field type.
+   */
+  protected static $datetimeType = DateRangeItem::DATETIME_TYPE_DATETIME;
+
+  /**
    * {@inheritdoc}
    */
   public static $modules = ['datetime', 'datetime_range', 'entity_test'];
@@ -58,7 +63,7 @@ public function setUp() {
       'field_name' => static::$fieldName,
       'type' => 'daterange',
       'entity_type' => static::$entityTypeId,
-      'settings' => ['datetime_type' => DateRangeItem::DATETIME_TYPE_DATETIME],
+      'settings' => ['datetime_type' => static::$datetimeType],
     ])
       ->save();
 
@@ -66,7 +71,6 @@ public function setUp() {
       'field_name' => static::$fieldName,
       'entity_type' => static::$entityTypeId,
       'bundle' => $this->entity->bundle(),
-//      'settings' => ['default_value' => static::$startDateString],
     ])
       ->save();
 
@@ -137,46 +141,54 @@ protected function assertNormalizationEdgeCases($method, Url $url, array $reques
 
       // DX: 422 when date type is incorrect.
 
-      // Errors?
       $value = ['2017', '03', '01', '21', '53', '00'];
       $end_value = static::$endDateString;
-      $message = "Unprocessable Entity: validation failed.\n{$fieldName}.0: The daterange start value must be a string.\n{$fieldName}.0: The daterange end value must be a string.\n{$fieldName}.0.value: This value should be of the correct primitive type.\n{$fieldName}.0.end_value: This value should be of the correct primitive type.\n";
+      $message = "Unprocessable Entity: validation failed.\n{$fieldName}.0: The date range start value must be a string.\n{$fieldName}.0.value: This value should be of the correct primitive type.\n";
       $this->doEdgeCaseCall($method, $url, $request_options, $value, $end_value, $message);
 
-      // Works!
       $value = static::$startDateString;
       $end_value = ['2017', '03', '02', '21', '53', '00'];
-      $message = "Unprocessable Entity: validation failed.\n{$fieldName}.0: The daterange end value must be a string.\n{$fieldName}.0.end_value: This value should be of the correct primitive type.\n";
+      $message = "Unprocessable Entity: validation failed.\n{$fieldName}.0: The date range end value must be a string.\n{$fieldName}.0.end_value: This value should be of the correct primitive type.\n";
       $this->doEdgeCaseCall($method, $url, $request_options, $value, $end_value, $message);
 
-      // Works??
       $value = ['2017', '03', '01', '21', '53', '00'];
       $end_value = ['2017', '03', '02', '21', '53', '00'];
-      $message = "Unprocessable Entity: validation failed.\n{$fieldName}.0: The daterange start value must be a string.\n{$fieldName}.0: The daterange end value must be a string.\n{$fieldName}.0.value: This value should be of the correct primitive type.\n{$fieldName}.0.end_value: This value should be of the correct primitive type.\n";
+      $message = "Unprocessable Entity: validation failed.\n{$fieldName}.0: The date range start value must be a string.\n{$fieldName}.0: The date range end value must be a string.\n{$fieldName}.0.value: This value should be of the correct primitive type.\n{$fieldName}.0.end_value: This value should be of the correct primitive type.\n";
       $this->doEdgeCaseCall($method, $url, $request_options, $value, $end_value, $message);
 
-      // @todo Adjust the stuff below...
-      return;
-
       // DX: 422 when date format is incorrect.
-      $normalization = $this->getNormalizedPostEntity();
+
       $value = '2017-03-01';
-      $normalization[static::$fieldName][0]['value'] = $value;
+      $end_value = static::$endDateString;
+      $message = "Unprocessable Entity: validation failed.\n{$fieldName}.0: The date range start value '{$value}' is invalid for the format '{$fieldFormat}'\n";
+      $this->doEdgeCaseCall($method, $url, $request_options, $value, $end_value, $message);
+
+      $value = static::$startDateString;
+      $end_value = '2017-03-02';
+      $message = "Unprocessable Entity: validation failed.\n{$fieldName}.0: The date range end value '{$end_value}' is invalid for the format '{$fieldFormat}'\n";
+      $this->doEdgeCaseCall($method, $url, $request_options, $value, $end_value, $message);
 
-      $request_options[RequestOptions::BODY] = $this->serializer->encode($normalization, static::$format);
-      $response = $this->request($method, $url, $request_options);
-      $message = "Unprocessable Entity: validation failed.\n{$fieldName}.0: The daterange start value '{$value}' is invalid for the format '{$fieldFormat}'\n";
-      $this->assertResourceErrorResponse(422, $message, $response);
+      $value = '2017-03-01';
+      $end_value = '2017-03-02';
+      $message = "Unprocessable Entity: validation failed.\n{$fieldName}.0: The date range start value '{$value}' is invalid for the format '{$fieldFormat}'\n{$fieldName}.0: The date range end value '{$end_value}' is invalid for the format '{$fieldFormat}'\n";
+      $this->doEdgeCaseCall($method, $url, $request_options, $value, $end_value, $message);
 
       // DX: 422 when date format is incorrect.
-      $normalization = $this->getNormalizedPostEntity();
+
       $value = '2017-13-55T20:02:00';
-      $normalization[static::$fieldName][0]['value'] = $value;
+      $end_value = static::$endDateString;
+      $message = "Unprocessable Entity: validation failed.\n{$fieldName}.0: The date range start value '{$value}' did not parse properly for the format '{$fieldFormat}'\n{$fieldName}.0.value: This value should be of the correct primitive type.\n";
+      $this->doEdgeCaseCall($method, $url, $request_options, $value, $end_value, $message);
 
-      $request_options[RequestOptions::BODY] = $this->serializer->encode($normalization, static::$format);
-      $response = $this->request($method, $url, $request_options);
-      $message = "Unprocessable Entity: validation failed.\n{$fieldName}.0: The daterange start value '{$value}' did not parse properly for the format '{$fieldFormat}'\n{$fieldName}.0.value: This value should be of the correct primitive type.\n";
-      $this->assertResourceErrorResponse(422, $message, $response);
+      $value = static::$startDateString;
+      $end_value = '2017-13-56T20:02:00';
+      $message = "Unprocessable Entity: validation failed.\n{$fieldName}.0: The date range end value '{$end_value}' did not parse properly for the format '{$fieldFormat}'\n{$fieldName}.0.end_value: This value should be of the correct primitive type.\n";
+      $this->doEdgeCaseCall($method, $url, $request_options, $value, $end_value, $message);
+
+      $value = '2017-13-55T20:02:00';
+      $end_value = '2017-13-56T20:02:00';
+      $message = "Unprocessable Entity: validation failed.\n{$fieldName}.0: The date range start value '{$value}' did not parse properly for the format '{$fieldFormat}'\n{$fieldName}.0: The date range end value '{$end_value}' did not parse properly for the format '{$fieldFormat}'\n{$fieldName}.0.value: This value should be of the correct primitive type.\n{$fieldName}.0.end_value: This value should be of the correct primitive type.\n";
+      $this->doEdgeCaseCall($method, $url, $request_options, $value, $end_value, $message);
     }
   }
 
@@ -190,11 +202,11 @@ protected function assertNormalizationEdgeCases($method, Url $url, array $reques
    * @param array $request_options
    *   Request options to apply.
    * @var mixed $value
-   *   Foo.
+   *   The test start date value.
    * @var mixed $end_value
-   *   Foo.
+   *   The test end date value.
    * @var string $message
-   *   Foo.
+   *   The expected error message.
    */
   protected function doEdgeCaseCall($method, Url $url, array $request_options, $value, $end_value, $message) {
     $normalization = $this->getNormalizedPostEntity();