diff --git a/core/lib/Drupal/Component/Gettext/PoStreamReader.php b/core/lib/Drupal/Component/Gettext/PoStreamReader.php
index f84d251..eb62831 100644
--- a/core/lib/Drupal/Component/Gettext/PoStreamReader.php
+++ b/core/lib/Drupal/Component/Gettext/PoStreamReader.php
@@ -424,6 +424,9 @@ private function readLine() {
           $this->_current_item['msgstr'] = [];
         }
 
+        // Replace @count[X] elements with @count. For compatibility with
+        // drupal.org translations for Drupal 7.
+        $quoted = preg_replace('!@count\[\d+\]!', '@count', $quoted);
         $this->_current_item['msgstr'][$this->_current_plural_index] = $quoted;
 
         $this->_context = 'MSGSTR_ARR';
diff --git a/core/modules/locale/locale.batch.inc b/core/modules/locale/locale.batch.inc
index fade172..0e38f1e 100644
--- a/core/modules/locale/locale.batch.inc
+++ b/core/modules/locale/locale.batch.inc
@@ -303,3 +303,76 @@ function locale_translation_download_source($source_file, $directory = 'temporar
   \Drupal::logger('locale')->error('Unable to download translation file @uri.', ['@uri' => $source_file->uri]);
   return FALSE;
 }
+
+/**
+ * Implements callback_batch_operation().
+ *
+ * Executes a batch operation for locale_update_8400().
+ *
+ * @param array|\ArrayAccess $context
+ *   An array of contextual key/values.
+ */
+function _locale_fix_old_plural_style_batch_proccess(&$context) {
+  $database = \Drupal::database();
+
+  if (!isset($context['sandbox']['progress'])) {
+    $context['sandbox']['progress'] = 0;
+    $context['sandbox']['max'] = $database->query('SELECT COUNT(lid) FROM {locales_target} WHERE translation REGEXP :pattern', [':pattern' =>  "@count\\[[0-9]+\\]"])->fetchField();
+  }
+
+  $limit = 100;
+
+  $result = $database->queryRange("SELECT lid, translation FROM {locales_target} WHERE translation REGEXP '@count\\\[[0-9]+\\\]'", 0, $limit)->fetchAll();
+
+  foreach ($result as $row) {
+    $lid = $row->lid;
+    $old_translation = $row->translation;
+    $new_translation = preg_replace('!@count\[\d+\]!', '@count', $old_translation);
+    $database->query(
+      "UPDATE {locales_target} SET translation = :new_translation WHERE lid = :lid",
+      [
+        ':new_translation' => $new_translation,
+        ':lid' => $lid,
+      ]
+    );
+    $context['results'][] = "$lid: $old_translation ---> $new_translation";
+    $context['sandbox']['progress']++;
+  }
+
+  if ($context['sandbox']['progress'] != $context['sandbox']['max']) {
+    $context['finished'] = $context['sandbox']['progress'] / $context['sandbox']['max'];
+  }
+
+}
+
+/**
+ * Implements callback_batch_finished().
+ *
+ * Reports the 'finished' status of batch operation for node_mass_update().
+ *
+ * @param bool $success
+ *   A boolean indicating whether the batch mass update operation successfully
+ *   concluded.
+ * @param string[] $results
+ *   An array of rendered links to nodes updated via the batch mode process.
+ * @param array $operations
+ *   An array of function calls (not used in this function).
+ *
+ * @see _locale_fix_old_plural_style_batch_proccess()
+ */
+function _locale_fix_old_plural_style_batch_finished($success, $results, $operations) {
+  if ($success) {
+    drupal_set_message(t('The update has been performed.'));
+  }
+  else {
+    drupal_set_message(t('An error occurred and processing did not complete.'), 'error');
+  }
+  drupal_set_message(t('Count changes: @count.', ['@count' => count($results)]));
+//  $item_list = [
+//    '#theme' => 'item_list',
+//    '#items' => $results,
+//  ];
+//  $message = \Drupal::service('renderer')->renderPlain($item_list);
+//  drupal_set_message($message);
+
+}
diff --git a/core/modules/locale/locale.install b/core/modules/locale/locale.install
index 225e952..dba403f 100644
--- a/core/modules/locale/locale.install
+++ b/core/modules/locale/locale.install
@@ -303,3 +303,20 @@ function locale_update_8300() {
   // the new key value collection.
   \Drupal::state()->delete('locale.translation_status');
 }
+
+/**
+ * Fix old plural style.
+ */
+function locale_update_8400() {
+  $batch = [
+    'operations' => [
+      ['_locale_fix_old_plural_style_batch_proccess', []]
+    ],
+    'finished' => '_locale_fix_old_plural_style_batch_finished',
+    'title' => t('Processing'),
+    'progress_message' => '',
+    'error_message' => t('The update has encountered an error.'),
+    'file' => drupal_get_path('module', 'locale') . '/locale.batch.inc',
+  ];
+  batch_set($batch);
+}
diff --git a/core/modules/locale/tests/src/Functional/LocaleImportFunctionalTest.php b/core/modules/locale/tests/src/Functional/LocaleImportFunctionalTest.php
index 581c98f..97f6dee 100644
--- a/core/modules/locale/tests/src/Functional/LocaleImportFunctionalTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleImportFunctionalTest.php
@@ -362,6 +362,17 @@ public function testCreatedLanguageTranslation() {
   }
 
   /**
+   * Test the translation are imported with fix old plural style.
+   */
+  public function testCreatedLanguageTranslationWithOldPluralStyle() {
+    $this->importPoFile($this->getPoFileWithOldPluralStyle(), ['langcode' => 'ru']);
+    for ($i=0; $i < 6; $i++) {
+      $plural = \Drupal::translation()->formatPlural($i, '1 word', '@count words', [], ['langcode' => 'ru']);
+      $this->assertSame("word$i", $plural->render(), 'Import old "@count[number]" plural style.');
+    }
+  }
+
+  /**
    * Helper function: import a standalone .po file in a given language.
    *
    * @param string $contents
@@ -640,4 +651,29 @@ public function getPoFileWithConfigDe() {
 EOF;
   }
 
+  /**
+   * Helper function that returns a .po file with old plural style.
+   */
+  public function getPoFileWithOldPluralStyle() {
+    return <<< EOF
+msgid ""
+msgstr ""
+"Project-Id-Version: Drupal 8\\n"
+"MIME-Version: 1.0\\n"
+"Content-Type: text/plain; charset=UTF-8\\n"
+"Content-Transfer-Encoding: 8bit\\n"
+"Plural-Forms: nplurals=5; plural=n;\\n"
+
+msgid "1 word"
+msgid_plural "@count words"
+msgstr[0] "@count[0] word0"
+msgstr[1] "@count[1] word1"
+msgstr[2] "@count[2] word2"
+msgstr[3] "@count[3] word3"
+msgstr[4] "@count[4] word4"
+msgstr[5] "@count[5] word5"
+
+EOF;
+  }
+
 }