diff -u b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
--- b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
+++ b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
@@ -527,7 +527,7 @@
       'destination_module' => 'taxonomy',
     ],
     'd6_i18n_taxonomy_vocabulary' => [
-      'source_module' => 'taxonomy',
+      'source_module' => 'i18n',
       'destination_module' => 'taxonomy',
     ],
     'd6_term_node' => [
reverted:
--- b/core/modules/taxonomy/tests/src/Kernel/Migrate/d6/MigrateTaxonomyVocabularyTest.php
+++ a/core/modules/taxonomy/tests/src/Kernel/Migrate/d6/MigrateTaxonomyVocabularyTest.php
@@ -15,14 +15,14 @@
   /**
    * {@inheritdoc}
    */
+  public static $modules = array('taxonomy');
-  public static $modules = ['config_translation', 'locale', 'language', 'taxonomy'];
 
   /**
    * {@inheritdoc}
    */
   protected function setUp() {
     parent::setUp();
+    $this->executeMigration('d6_taxonomy_vocabulary');
-    $this->executeMigrations(['d6_taxonomy_vocabulary', 'd6_i18n_taxonomy_vocabulary']);
   }
 
   /**
@@ -43,18 +43,6 @@
     $this->assertIdentical('description of vocabulary name much longer than thirty two characters', $vocabulary->getDescription());
     $this->assertIdentical(3, $vocabulary->getHierarchy());
     $this->assertIdentical(7, $vocabulary->get('weight'));
-
-    $language_manager =  \Drupal::service('language_manager');
-    $config = $language_manager->getLanguageConfigOverride('fr', 'taxonomy.vocabulary.vocabulary_1_i_0_');
-    $this->assertSame('fr - vocabulary 1 (i=0)', $config->get('name'));
-    $config = $language_manager->getLanguageConfigOverride('fr', 'taxonomy.vocabulary.vocabulary_2_i_1_');
-    $this->assertSame('fr - vocabulary 2 (i=1)', $config->get('name'));
-    $config = $language_manager->getLanguageConfigOverride('fr', 'taxonomy.vocabulary.vocabulary_3_i_2_');
-    $this->assertSame('fr - vocabulary 3 (i=2)', $config->get('name'));
-    $config = $language_manager->getLanguageConfigOverride('fr', 'taxonomy.vocabulary.vocabulary_name_much_longer_than');
-    $this->assertSame('Nom de vocabulaire beaucoup plus long que trente-deux caractères', $config->get('name'));
-    $config = $language_manager->getLanguageConfigOverride('fr', 'taxonomy.vocabulary.tags');
-    $this->assertSame('fr - Tags', $config->get('name'));
   }
 
 }
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/config_translation/tests/src/Kernel/Migrate/d6/MigrateI18nTaxonomyVocabularyTest.php
@@ -0,0 +1,52 @@
+<?php
+
+namespace Drupal\Tests\config_translation\Kernel\Migrate\d6;
+
+use Drupal\Tests\migrate_drupal\Kernel\d6\MigrateDrupal6TestBase;
+
+/**
+ * Migrate taxonomy vocabularies to taxonomy.vocabulary.*.yml.
+ *
+ * @group migrate_drupal_6
+ */
+class MigrateI18nTaxonomyVocabularyTest extends MigrateDrupal6TestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = [
+    'config_translation',
+    'locale',
+    'language',
+    'taxonomy',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $this->executeMigrations([
+      'd6_taxonomy_vocabulary',
+      'd6_i18n_taxonomy_vocabulary',
+    ]);
+  }
+
+  /**
+   * Tests the Drupal 6 i18n taxonomy vocabularies to Drupal 8 migration.
+   */
+  public function testI18nTaxonomyVocabulary() {
+    $language_manager = \Drupal::service('language_manager');
+    $config = $language_manager->getLanguageConfigOverride('fr', 'taxonomy.vocabulary.vocabulary_1_i_0_');
+    $this->assertSame('fr - vocabulary 1 (i=0)', $config->get('name'));
+    $config = $language_manager->getLanguageConfigOverride('fr', 'taxonomy.vocabulary.vocabulary_2_i_1_');
+    $this->assertSame('fr - vocabulary 2 (i=1)', $config->get('name'));
+    $config = $language_manager->getLanguageConfigOverride('fr', 'taxonomy.vocabulary.vocabulary_3_i_2_');
+    $this->assertSame('fr - vocabulary 3 (i=2)', $config->get('name'));
+    $config = $language_manager->getLanguageConfigOverride('fr', 'taxonomy.vocabulary.vocabulary_name_much_longer_than');
+    $this->assertSame('Nom de vocabulaire beaucoup plus long que trente-deux caractères', $config->get('name'));
+    $config = $language_manager->getLanguageConfigOverride('fr', 'taxonomy.vocabulary.tags');
+    $this->assertSame('fr - Tags', $config->get('name'));
+  }
+
+}