diff --git a/core/modules/datetime/src/Plugin/Field/FieldWidget/DateRangeWidgetBase.php b/core/modules/datetime/src/Plugin/Field/FieldWidget/DateRangeWidgetBase.php
index 418f7f5..08d635e 100644
--- a/core/modules/datetime/src/Plugin/Field/FieldWidget/DateRangeWidgetBase.php
+++ b/core/modules/datetime/src/Plugin/Field/FieldWidget/DateRangeWidgetBase.php
@@ -98,6 +98,9 @@ public function massageFormValues(array $values, array $form, FormStateInterface
           case DateRangeItem::DATERANGE_TYPE_ALLDAY:
             // All day field start at midnight on the starting date, but are
             // stored like datetime fields, so we need to adjust the time.
+            // This function is called twice, so to prevent a double conversion
+            // we need to explicitly set the timezone.
+            $start_date->setTimeZone(timezone_open(drupal_get_user_timezone()));
             $start_date->setTime(0, 0, 0);
             $format = DATETIME_DATETIME_STORAGE_FORMAT;
             break;
@@ -125,6 +128,9 @@ public function massageFormValues(array $values, array $form, FormStateInterface
           case DateRangeItem::DATERANGE_TYPE_ALLDAY:
             // All day field end at midnight on the end date, but are
             // stored like datetime fields, so we need to adjust the time.
+            // This function is called twice, so to prevent a double conversion
+            // we need to explicitly set the timezone.
+            $end_date->setTimeZone(timezone_open(drupal_get_user_timezone()));
             $end_date->setTime(23, 59, 59);
             $format = DATETIME_DATETIME_STORAGE_FORMAT;
             break;
diff --git a/core/modules/datetime/src/Tests/DateRangeFieldTest.php b/core/modules/datetime/src/Tests/DateRangeFieldTest.php
index 08cbc8f..556a6fa 100644
--- a/core/modules/datetime/src/Tests/DateRangeFieldTest.php
+++ b/core/modules/datetime/src/Tests/DateRangeFieldTest.php
@@ -407,7 +407,7 @@ function testDatelistWidget() {
         ],
       ])
       ->save();
-    \Drupal::entityManager()->clearCachedFieldDefinitions();
+    \Drupal::service('entity_field.manager')->clearCachedFieldDefinitions();
 
     // Display creation form.
     $this->drupalGet('entity_test/add');
@@ -440,7 +440,7 @@ function testDatelistWidget() {
         ],
       ])
       ->save();
-    \Drupal::entityManager()->clearCachedFieldDefinitions();
+    \Drupal::service('entity_field.manager')->clearCachedFieldDefinitions();
 
     // Display creation form.
     $this->drupalGet('entity_test/add');
@@ -475,7 +475,7 @@ function testDatelistWidget() {
         ],
       ])
       ->save();
-    \Drupal::entityManager()->clearCachedFieldDefinitions();
+    \Drupal::service('entity_field.manager')->clearCachedFieldDefinitions();
 
     // Go to the form display page to assert that increment option does appear on Date Time
     $fieldEditUrl = 'entity_test/structure/entity_test/form-display';
@@ -573,7 +573,7 @@ function testDatelistWidget() {
         ],
       ])
       ->save();
-    \Drupal::entityManager()->clearCachedFieldDefinitions();
+    \Drupal::service('entity_field.manager')->clearCachedFieldDefinitions();
 
     // Display creation form.
     $this->drupalGet('entity_test/add');
@@ -626,7 +626,7 @@ function testDatelistWidget() {
         ],
       ])
       ->save();
-    \Drupal::entityManager()->clearCachedFieldDefinitions();
+    \Drupal::service('entity_field.manager')->clearCachedFieldDefinitions();
 
     // Test the widget for validation notifications.
     foreach ($this->datelistDataProvider() as $data) {
@@ -798,7 +798,7 @@ function testDefaultValue() {
     ], 'Default value has been stored successfully');
 
     // Clear field cache in order to avoid stale cache values.
-    \Drupal::entityManager()->clearCachedFieldDefinitions();
+    \Drupal::service('entity_field.manager')->clearCachedFieldDefinitions();
 
     // Create a new node to check that datetime field default value is today.
     $new_node = Node::create(['type' => 'date_content']);
@@ -851,7 +851,7 @@ function testDefaultValue() {
     ], 'Default value has been stored successfully');
 
     // Clear field cache in order to avoid stale cache values.
-    \Drupal::entityManager()->clearCachedFieldDefinitions();
+    \Drupal::service('entity_field.manager')->clearCachedFieldDefinitions();
 
     // Create a new node to check that datetime field default value is +90 days.
     $new_node = Node::create(['type' => 'date_content']);
@@ -879,7 +879,7 @@ function testDefaultValue() {
     $this->assertTrue(empty($config_entity['default_value']), 'Empty default value has been stored successfully');
 
     // Clear field cache in order to avoid stale cache values.
-    \Drupal::entityManager()->clearCachedFieldDefinitions();
+    \Drupal::service('entity_field.manager')->clearCachedFieldDefinitions();
 
     // Create a new node to check that datetime field default value is not set.
     $new_node = Node::create(['type' => 'date_content']);
@@ -1065,6 +1065,24 @@ function testInvalidField() {
     ];
     $this->drupalPostForm(NULL, $edit, t('Save'));
     $this->assertText('date is invalid', format_string('Invalid end second value %time has been caught.', ['%time' => $time_value]));
+
+    $edit = [
+      "{$field_name}[0][value][date]" => '2012-12-01',
+      "{$field_name}[0][value][time]" => '12:00:00',
+      "{$field_name}[0][value2][date]" => '2010-12-01',
+      "{$field_name}[0][value2][time]" => '12:00:00',
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('Start date should be equal to, or before, end date', 'End date before start date has been caught.');
+
+    $edit = [
+      "{$field_name}[0][value][date]" => '2012-12-01',
+      "{$field_name}[0][value][time]" => '12:00:00',
+      "{$field_name}[0][value2][date]" => '2012-12-01',
+      "{$field_name}[0][value2][time]" => '11:00:00',
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('Start date should be equal to, or before, end date', 'End time before start time has been caught.');
   }
 
   /**