diff --git a/core/modules/locale/locale.post_update.php b/core/modules/locale/locale.post_update.php
new file mode 100644
index 0000000000..91728f305e
--- /dev/null
+++ b/core/modules/locale/locale.post_update.php
@@ -0,0 +1,13 @@
+<?php
+
+/**
+ * @file
+ * Post-update functions for Locale module.
+ */
+
+/**
+ * Clear cache to ensure translations with old style are clear.
+ */
+function locale_post_update_clear_cache_for_old_translations() {
+  // Remove cache of translations, like '@count[2] words'.
+}
diff --git a/core/modules/locale/src/LocaleLookup.php b/core/modules/locale/src/LocaleLookup.php
index 9290efc305..6380c36757 100644
--- a/core/modules/locale/src/LocaleLookup.php
+++ b/core/modules/locale/src/LocaleLookup.php
@@ -7,6 +7,7 @@
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Language\LanguageManagerInterface;
 use Drupal\Core\Lock\LockBackendInterface;
+use Drupal\Core\StringTranslation\PluralTranslatableMarkup;
 use Symfony\Component\HttpFoundation\RequestStack;
 
 /**
@@ -172,6 +173,11 @@ protected function resolveCacheMiss($offset) {
       }
     }
 
+    if (is_string($value) && strpos($value, PluralTranslatableMarkup::DELIMITER) !== FALSE) {
+      // Fix old style plural problem, when value contains @count[number].
+      $value = preg_replace('!@count\[\d+\]!', '@count', $value);
+    }
+
     $this->storage[$offset] = $value;
     // Disabling the usage of string caching allows a module to watch for
     // the exact list of strings used on a page. From a performance
diff --git a/core/modules/locale/tests/src/Functional/LocaleLocaleLookupTest.php b/core/modules/locale/tests/src/Functional/LocaleLocaleLookupTest.php
index 5f3e5f7e80..0938895083 100644
--- a/core/modules/locale/tests/src/Functional/LocaleLocaleLookupTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleLocaleLookupTest.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\Tests\locale\Functional;
 
+use Drupal\Core\StringTranslation\PluralTranslatableMarkup;
 use Drupal\language\Entity\ConfigurableLanguage;
 use Drupal\Tests\BrowserTestBase;
 
@@ -55,4 +56,46 @@ public function testLanguageFallbackDefaults() {
     $this->assertEqual($context['operation'], 'locale_lookup');
   }
 
+  /**
+   * Test old plural style @count[number] fix.
+   *
+   * @dataProvider providerTestFixOldPluralStyle
+   */
+  public function testFixOldPluralStyle($translation_value, $expected) {
+    /** @var \Drupal\locale\StringDatabaseStorage $string_storage */
+    $string_storage = \Drupal::service('locale.storage');
+
+    $string = $string_storage->findString(['source' => 'Member for', 'context' => '']);
+
+    // Create translation with old @count[2] plural style.
+    $string_storage->createTranslation([
+      'lid' => $string->getId(),
+      'language' => 'fr',
+      'translation' => $translation_value,
+    ])->save();
+
+    drupal_flush_all_caches();
+    $this->drupalGet('');
+    $this->assertSession()->pageTextContains($expected);
+
+    // Assert that source not changed.
+    $translation = $string_storage->findTranslation(['language' => 'fr', 'lid' => $string->getId()])->translation;
+    $this->assertSame($translation_value, $translation);
+  }
+
+  /**
+   * Provides data for testFixOldPluralStyle().
+   *
+   * @return array
+   *   An array of test data:
+   *     - translation value
+   *     - expected result
+   */
+  public function providerTestFixOldPluralStyle() {
+    return [
+      'non-plural translation' => ['@count[2] non-plural test', '@count[2] non-plural test'],
+      'plural translation' => ['@count[2] plural test' . PluralTranslatableMarkup::DELIMITER, '@count plural test'],
+    ];
+  }
+
 }
diff --git a/core/modules/locale/tests/src/Unit/LocaleLookupTest.php b/core/modules/locale/tests/src/Unit/LocaleLookupTest.php
index cbdd6deabb..42ecedb707 100644
--- a/core/modules/locale/tests/src/Unit/LocaleLookupTest.php
+++ b/core/modules/locale/tests/src/Unit/LocaleLookupTest.php
@@ -3,6 +3,7 @@
 namespace Drupal\Tests\locale\Unit;
 
 use Drupal\Core\DependencyInjection\ContainerBuilder;
+use Drupal\Core\StringTranslation\PluralTranslatableMarkup;
 use Drupal\locale\LocaleLookup;
 use Drupal\Tests\UnitTestCase;
 use Symfony\Component\HttpFoundation\Request;
@@ -266,4 +267,66 @@ public function testResolveCacheMissNoTranslation() {
     $this->assertTrue($locale_lookup->get('test'));
   }
 
+  /**
+   * Tests locale lookups with old plural style of translations.
+   *
+   * @param array $translations
+   *   The source with translations.
+   * @param string $langcode
+   *   The language code of translation string.
+   * @param string $string
+   *   The string for translation.
+   * @param bool $is_fix
+   *   The flag about expected fix translation.
+   *
+   * @covers ::resolveCacheMiss
+   * @dataProvider providerFixOldPluralTranslationProvider
+   */
+  public function testFixOldPluralStyleTranslations($translations, $langcode, $string, $is_fix) {
+    $this->storage->expects($this->any())
+      ->method('findTranslation')
+      ->will($this->returnCallback(function ($argument) use ($translations) {
+        if (isset($translations[$argument['language']][$argument['source']])) {
+          return (object) ['translation' => $translations[$argument['language']][$argument['source']]];
+        }
+        return TRUE;
+      }));
+    $this->languageManager->expects($this->any())
+      ->method('getFallbackCandidates')
+      ->will($this->returnCallback(function (array $context = []) {
+        switch ($context['langcode']) {
+          case 'by':
+            return ['ru'];
+        }
+      }));
+    $this->cache->expects($this->once())
+      ->method('get')
+      ->with('locale:' . $langcode . '::anonymous', FALSE);
+
+    $locale_lookup = new LocaleLookup($langcode, '', $this->storage, $this->cache, $this->lock, $this->configFactory, $this->languageManager, $this->requestStack);
+    $this->assertSame($is_fix, strpos($locale_lookup->get($string), '@count[2]') === FALSE);
+  }
+
+  /**
+   * Provides test data for testResolveCacheMissWithFallback().
+   */
+  public function providerFixOldPluralTranslationProvider() {
+    $translations = [
+      'by' => [
+        'word1' => '@count[2] word-by',
+        'word2' => implode(PluralTranslatableMarkup::DELIMITER, ['word-by', '@count[2] word-by']),
+      ],
+      'ru' => [
+        'word3' => '@count[2] word-ru',
+        'word4' => implode(PluralTranslatableMarkup::DELIMITER, ['word-ru', '@count[2] word-ru']),
+      ],
+    ];
+    return [
+      'no-plural' => [$translations, 'by', 'word1', FALSE],
+      'no-plural from other language' => [$translations, 'by', 'word3', FALSE],
+      'plural' => [$translations, 'by', 'word2', TRUE],
+      'plural from other language' => [$translations, 'by', 'word4', TRUE],
+    ];
+  }
+
 }