Index: sites/all/modules/contrib/redis/lib/Redis/Lock/PhpRedis.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- sites/all/modules/contrib/redis/lib/Redis/Lock/PhpRedis.php	(date 1573581063000)
+++ sites/all/modules/contrib/redis/lib/Redis/Lock/PhpRedis.php	(date 1573592242251)
@@ -108,7 +108,7 @@

     if ($client->get($key) == $id) {
       $client->multi();
-      $client->delete($key);
+      $this->doDelete($client, $key);
       $client->exec();
     }
     else {
@@ -131,8 +131,28 @@
       $owner = $client->get($key);

       if (empty($owner) || $owner == $id) {
-        $client->delete($key);
-      }
+        $this->doDelete($client, $key);
+      }
+    }
+  }
+
+  /**
+   * Wrapper for deleting items.
+   *
+   * This is necessary because of API changes in Redis.
+   *
+   * @param object $client
+   *   The client object to work with.
+   * @param string $key
+   *   The item that needs to be deleted.
+   */
+  protected function doDelete($client, $key) {
+    if (method_exists($client, 'del')) {
+      $client->del($key);
+    }
+    else {
+      $client->delete($key);
     }
   }
+
 }