diff -u b/core/modules/menu_link_content/migrations/d6_menu_links_translation.yml b/core/modules/menu_link_content/migrations/d6_menu_links_translation.yml
--- b/core/modules/menu_link_content/migrations/d6_menu_links_translation.yml
+++ b/core/modules/menu_link_content/migrations/d6_menu_links_translation.yml
@@ -2,21 +2,20 @@
 label: Menu links
 migration_tags:
   - Drupal 6
+  - Content
 source:
   plugin: d6_menu_link_translation
 process:
   id: mlid
   langcode: language
-  skip:
-    plugin: skip_on_empty
-    method: row
-    source: migrate
+  description_untranslated: description
+  title_untranslated: link_title
   title:
     -
       plugin: callback
       source:
         - title_translated
-        - title_untranslated
+        - '@title_untranslated'
       callable: array_filter
     -
       plugin: callback
@@ -26,7 +25,7 @@
       plugin: callback
       source:
         - description_translated
-        - description_untranslated
+        - '@description_untranslated'
       callable: array_filter
     -
       plugin: callback
@@ -38,6 +37,9 @@
       migration: d6_menu
       source: menu_name
     -
+      plugin: skip_on_empty
+      method: row
+    -
       plugin: static_map
       map:
         management: admin
diff -u b/core/modules/menu_link_content/src/Plugin/migrate/source/d6/MenuLinkTranslation.php b/core/modules/menu_link_content/src/Plugin/migrate/source/d6/MenuLinkTranslation.php
--- b/core/modules/menu_link_content/src/Plugin/migrate/source/d6/MenuLinkTranslation.php
+++ b/core/modules/menu_link_content/src/Plugin/migrate/source/d6/MenuLinkTranslation.php
@@ -2,7 +2,7 @@
 
 namespace Drupal\menu_link_content\Plugin\migrate\source\d6;
 
-use Drupal\Component\Utility\Unicode;
+use Drupal\migrate\MigrateSkipRowException;
 use Drupal\migrate\Row;
 use Drupal\menu_link_content\Plugin\migrate\source\MenuLink;
 
@@ -48,21 +48,16 @@
    * {@inheritdoc}
    */
   public function prepareRow(Row $row) {
+    parent::prepareRow($row);
     $language = $row->getSourceProperty('language');
     $mlid = $row->getSourceProperty('mlid');
-    if (empty($this->idMap->lookupDestinationIds(['mlid' => $mlid, 'language' => $language]))) {
-      $row->setSourceProperty('migrate', TRUE);
-    }
-    // Set untranslated values as defaults.
-    $row->setSourceProperty('title_untranslated', $row->getSourceProperty('link_title'));
-    $row->setSourceProperty('options', unserialize($row->getSourceProperty('options')));
-    $row->setSourceProperty('description_untranslated', Unicode::truncate($row->getSourceProperty('options/attributes/title'), 255));
 
     // Save the translation for this property.
     $property = $row->getSourceProperty('property');
     $row->setSourceProperty($property . '_translated', $row->getSourceProperty('translation'));
 
-    // Get the translation for the property not already in the row.
+    // Get the translation, if one exists, for the property not already in the
+    // row.
     $other_property = ($property == 'title') ? 'description' : 'title';
     $query = $this->select('i18n_strings', 'i18n')
       ->fields('i18n', ['lid'])
diff -u b/core/modules/migrate/src/Plugin/migrate/id_map/Sql.php b/core/modules/migrate/src/Plugin/migrate/id_map/Sql.php
--- b/core/modules/migrate/src/Plugin/migrate/id_map/Sql.php
+++ b/core/modules/migrate/src/Plugin/migrate/id_map/Sql.php
@@ -563,9 +563,11 @@
     $conditions = [];
     foreach ($this->sourceIdFields() as $field_name => $db_field) {
       if ($is_associative) {
+        // Ensure to handle array elements with a NULL value.
         if (array_key_exists($field_name, $source_id_values)) {
           // Associative $source_id_values can have fields out of order.
           if (isset($source_id_values[$field_name])) {
+            // Only add a condition if the value is not NULL.
             $conditions[$db_field] = $source_id_values[$field_name];
           }
           unset($source_id_values[$field_name]);