diff --git a/core/modules/content_translation/src/Plugin/migrate/source/d7/EntityTranslationSettings.php b/core/modules/content_translation/src/Plugin/migrate/source/d7/EntityTranslationSettings.php
index 9719777624671d8e511a69bd82654364958b3088..f35a205ae4b48061efa94dc42d96ff0bcaad7299 100644
--- a/core/modules/content_translation/src/Plugin/migrate/source/d7/EntityTranslationSettings.php
+++ b/core/modules/content_translation/src/Plugin/migrate/source/d7/EntityTranslationSettings.php
@@ -65,7 +65,10 @@ protected function initializeIterator() {
 
     // Find out which vocabulary uses entity translation by looking at the
     // 'entity_translation_taxonomy' variable.
-    $vocabularies = array_keys(array_filter($results['entity_translation_taxonomy']));
+    $vocabularies = [];
+    if (isset($results['entity_translation_taxonomy']) && is_array($results['entity_translation_taxonomy'])) {
+      $vocabularies = array_keys(array_filter($results['entity_translation_taxonomy']));
+    }
 
     if (in_array('node', $entity_types, TRUE) && !empty($node_types)) {
       // For each node type that uses entity translation, check if a
diff --git a/core/modules/content_translation/tests/src/Kernel/Plugin/migrate/source/d7/EntityTranslationSettingsTest.php b/core/modules/content_translation/tests/src/Kernel/Plugin/migrate/source/d7/EntityTranslationSettingsTest.php
index 08f7bc44e9dcd304a47f7d2094bf8a73f3b2192b..db0d33292769047ccac994773534ae01dab6964c 100644
--- a/core/modules/content_translation/tests/src/Kernel/Plugin/migrate/source/d7/EntityTranslationSettingsTest.php
+++ b/core/modules/content_translation/tests/src/Kernel/Plugin/migrate/source/d7/EntityTranslationSettingsTest.php
@@ -112,6 +112,15 @@ public function providerSource() {
       ],
     ];
 
+    // Source data when taxonomy terms are translatable but the
+    // 'entity_translation_taxonomy' variable is not set.
+    $tests[3]['source_data']['variable'] = [
+      [
+        'name' => 'entity_translation_entity_types',
+        'value' => 'a:4:{s:7:"comment";i:0;s:4:"node";i:0;s:13:"taxonomy_term";i:1;s:4:"user";i:0;}',
+      ],
+    ];
+
     // Expected data when there's no entity type that uses entity translation.
     $tests[0]['expected_data'] = [];
 
@@ -235,6 +244,10 @@ public function providerSource() {
       ],
     ];
 
+    // Expected data when taxonomy terms are translatable but the
+    // 'entity_translation_taxonomy' variable is not set.
+    $tests[3]['expected_data'] = [];
+
     return $tests;
   }