reverted:
--- b/core/modules/config_translation/migration_templates/i18n_user_profile_field_instance.yml
+++ /dev/null
@@ -1,28 +0,0 @@
-id: i18n_user_profile_field_instance
-label: User profile field instance configuration
-migration_tags:
-  - Drupal 6
-source:
-  plugin: d6_i18n_profile_field
-  constants:
-    entity_type: user
-    bundle: user
-process:
-  langcode: language
-  entity_type: 'constants/entity_type'
-  bundle: 'constants/bundle'
-  field_name: name
-  property:
-    plugin: static_map
-    source: property
-    map:
-      title: label
-      options: options
-      explanation: description
-  translation: translation
-destination:
-  plugin: entity:field_config
-migration_dependencies:
-  required:
-    - user_profile_field
-    - user_profile_field_instance
diff -u b/core/modules/config_translation/src/Plugin/migrate/source/d6/I18nProfileField.php b/core/modules/config_translation/src/Plugin/migrate/source/d6/I18nProfileField.php
--- b/core/modules/config_translation/src/Plugin/migrate/source/d6/I18nProfileField.php
+++ b/core/modules/config_translation/src/Plugin/migrate/source/d6/I18nProfileField.php
@@ -1,17 +1,11 @@
 <?php
 
-/**
- * @file
- * Contains \Drupal\config_translation\Plugin\migrate\source\d6\i18nProfileField.
- */
-
 namespace Drupal\config_translation\Plugin\migrate\source\d6;
 
 use Drupal\migrate_drupal\Plugin\migrate\source\DrupalSqlBase;
-use Drupal\migrate\Row;
 
 /**
- * Profile field source from database.
+ * i18n strings profile field source from database.
  *
  * @MigrateSource(
  *   id = "d6_i18n_profile_field",
@@ -21,32 +15,10 @@
 class i18nProfileField extends DrupalSqlBase {
 
   /**
-   * The source table containing profile field info.
-   *
-   * @var string
-   */
-  protected $fieldTable;
-
-  /**
-   * The source table containing the profile values.
-   *
-   * @var string
-   */
-  protected $valueTable;
-
-  /**
    * {@inheritdoc}
    */
   public function query() {
-    if (empty($this->fieldTable) || empty($this->valueTable)) {
-      if ($this->getModuleSchemaVersion('system') >= 7000) {
-        $this->fieldTable = 'profile_field';
-      }
-      else {
-        $this->fieldTable = 'profile_fields';
-      }
-    }
-    $query = $this->select($this->fieldTable, 'pf')
+    $query = $this->select('profile_fields', 'pf')
       ->fields('pf', array('fid', 'name'))
       ->fields('i18n', array('property'))
       ->fields('lt', array('lid', 'translation', 'language'));
diff -u b/core/modules/migrate/src/Plugin/migrate/destination/EntityConfigBase.php b/core/modules/migrate/src/Plugin/migrate/destination/EntityConfigBase.php
--- b/core/modules/migrate/src/Plugin/migrate/destination/EntityConfigBase.php
+++ b/core/modules/migrate/src/Plugin/migrate/destination/EntityConfigBase.php
@@ -121,8 +121,12 @@
    *   The row object to update from.
    */
   protected function updateEntity(EntityInterface $entity, Row $row) {
-    if ($row->hasDestinationProperty('langcode') && ($this->languageManager instanceof ConfigurableLanguageManagerInterface)) {
-      // Then this is a row with a translation string.
+    // If this row has a language code and it is not the default language
+    // and the language manager is configurable then this is a row with a
+    // translation string.
+    if ($row->hasDestinationProperty('langcode') &&
+      ($row->getDestinationProperty('langcode') != $this->languageManager->getDefaultLanguage()->getId()) &&
+      ($this->languageManager instanceof ConfigurableLanguageManagerInterface)) {
       $config = $entity->getConfigDependencyName();
       $config_override = $this->languageManager->getLanguageConfigOverride($row->getDestinationProperty('langcode'), $config);
       $config_override->set(str_replace(Row::PROPERTY_SEPARATOR, '.', $row->getDestinationProperty('property')), $row->getDestinationProperty('translation'));
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/config_translation/migration_templates/d6_i18n_user_profile_field_instance.yml
@@ -0,0 +1,28 @@
+id: i18n_user_profile_field_instance
+label: User profile field instance configuration
+migration_tags:
+  - Drupal 6
+source:
+  plugin: d6_i18n_profile_field
+  constants:
+    entity_type: user
+    bundle: user
+process:
+  langcode: language
+  entity_type: 'constants/entity_type'
+  bundle: 'constants/bundle'
+  field_name: name
+  property:
+    plugin: static_map
+    source: property
+    map:
+      title: label
+      options: options
+      explanation: description
+  translation: translation
+destination:
+  plugin: entity:field_config
+migration_dependencies:
+  required:
+    - user_profile_field
+    - user_profile_field_instance