diff -u b/core/lib/Drupal/Core/Cache/DatabaseBackend.php b/core/lib/Drupal/Core/Cache/DatabaseBackend.php
--- b/core/lib/Drupal/Core/Cache/DatabaseBackend.php
+++ b/core/lib/Drupal/Core/Cache/DatabaseBackend.php
@@ -10,6 +10,7 @@
 use Drupal\Component\Utility\Crypt;
 use Drupal\Core\Database\Connection;
 use Drupal\Core\Database\SchemaObjectExistsException;
+use Drupal\Component\Transliteration\TransliterationInterface;
 
 /**
  * Defines a default cache implementation.
@@ -42,21 +43,31 @@
   protected $checksumProvider;
 
   /**
+   * The transliteration service.
+   *
+   * @var \Drupal\Component\Transliteration\TransliterationInterface
+   */
+  protected $transliteration;
+
+  /**
    * Constructs a DatabaseBackend object.
    *
    * @param \Drupal\Core\Database\Connection $connection
    *   The database connection.
    * @param \Drupal\Core\Cache\CacheTagsChecksumInterface $checksum_provider
    *   The cache tags checksum provider.
+   * @param \Drupal\Component\Transliteration\TransliterationInterface $transliteration
+   *   The transliteration service.
    * @param string $bin
    *   The cache bin for which the object is created.
    */
-  public function __construct(Connection $connection, CacheTagsChecksumInterface $checksum_provider, $bin) {
+  public function __construct(Connection $connection, CacheTagsChecksumInterface $checksum_provider, TransliterationInterface $transliteration, $bin) {
     // All cache tables should be prefixed with 'cache_'.
     $bin = 'cache_' . $bin;
 
     $this->bin = $bin;
     $this->connection = $connection;
+    $this->transliteration = $transliteration;
     $this->checksumProvider = $checksum_provider;
   }
 
@@ -419,16 +430,20 @@
    *   The passed in cache ID.
    *
    * @return string
-   *   A cache ID that is at most 255 characters long.
+   *   An ASCII-encoded cache ID that is at most 255 characters long.
    */
   protected function normalizeCid($cid) {
-    // Nothing to do if the ID length is 255 characters or less.
-    if (strlen($cid) <= 255) {
+    // Nothing to do if the ID is a US ASCII string of 255 characters or less.
+    $cid_is_ascii = mb_check_encoding($cid, 'ASCII');
+    if (strlen($cid) <= 255 && $is_ascii === TRUE) {
       return $cid;
     }
     // Return a string that uses as much as possible of the original cache ID
     // with the hash appended.
     $hash = Crypt::hashBase64($cid);
+    if (!$cid_is_ascii) {
+      $cid = $this->transliteration->transliterate($cid);
+    }
     return substr($cid, 0, 255 - strlen($hash)) . $hash;
   }
 
only in patch2:
unchanged:
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -133,7 +133,7 @@ services:
       - [setContainer, ['@service_container']]
   cache.backend.database:
     class: Drupal\Core\Cache\DatabaseBackendFactory
-    arguments: ['@database', '@cache_tags.invalidator.checksum']
+    arguments: ['@database', '@cache_tags.invalidator.checksum', '@transliteration']
   cache.backend.apcu:
     class: Drupal\Core\Cache\ApcuBackendFactory
     arguments: ['@app.root', '@cache_tags.invalidator.checksum']