diff -u b/src/Element/Tablefield.php b/src/Element/Tablefield.php
--- b/src/Element/Tablefield.php
+++ b/src/Element/Tablefield.php
@@ -101,6 +101,7 @@
             'class' => ['table-rows-weight'],
           ],
         ],
+        '#weight' => $weight,
       ];
 
       $draggable = TRUE;
@@ -137,7 +138,7 @@
 
     // Sort rows by weight. This step is required so that the table stays
     // properly ordered when doing ajax operations.
-    uasort($weightedRows, ['Drupal\Component\Utility\SortArray', 'sortByWeightElement']);
+    uasort($weightedRows, ['Drupal\Component\Utility\SortArray', 'sortByWeightProperty']);
     $element['tablefield']['table'] += $weightedRows;
 
     // To change number of rows.
diff -u b/src/Plugin/Field/FieldFormatter/TablefieldFormatter.php b/src/Plugin/Field/FieldFormatter/TablefieldFormatter.php
--- b/src/Plugin/Field/FieldFormatter/TablefieldFormatter.php
+++ b/src/Plugin/Field/FieldFormatter/TablefieldFormatter.php
@@ -152,7 +152,6 @@
 
         // Run the table through input filters.
         foreach ($tabledata as $row_key => &$row) {
-          unset($row['weight']);
           foreach ($row as $col_key => $cell) {
             $tabledata[$row_key][$col_key] = [
               'data' => empty($table->format) ? $cell : check_markup($cell, $table->format),
only in patch2:
unchanged:
--- a/src/Plugin/Field/FieldWidget/TablefieldWidget.php
+++ b/src/Plugin/Field/FieldWidget/TablefieldWidget.php
@@ -204,6 +204,20 @@ class TablefieldWidget extends WidgetBase implements ContainerFactoryPluginInter
     }
   }
 
+  /**
+   * {@inheritDoc}
+   */
+  public function massageFormValues(array $values, array $form, FormStateInterface $form_state) {
+    foreach ($values as &$value) {
+      $rows = &$value['tablefield']['table'];
+      foreach ($rows as &$row) {
+        unset($row['weight']);
+      }
+    }
+
+    return parent::massageFormValues($values, $form, $form_state);
+  }
+
   /**
    * {@inheritdoc}
    *