Title: PHP Fatal error Uncaught Error: Call to undefined method WP_Object_Cache::flush_
Last modified: January 4, 2023

---

# PHP Fatal error Uncaught Error: Call to undefined method WP_Object_Cache::flush_

 *  Resolved [Mukesh Patel](https://wordpress.org/support/users/themukeshpatel/)
 * (@themukeshpatel)
 * [3 years, 4 months ago](https://wordpress.org/support/topic/php-fatal-error-uncaught-error-call-to-undefined-method-wp_object_cacheflush_/)
 * I am using Rank Math pluging. With that, LiteSpeed Cache plugin having issue.
   Below is messege.
 *     ```wp-block-code
       PHP Fatal error Uncaught Error: Call to undefined method WP_Object_Cache::flush_group() in /home/actualpost.com/public_html/wp-content/plugins/litespeed-cache/src/object.lib.php:307
       ```
   
 * I am using Redis Object Cache and I am getting this after moving to OpenLiteSpeed
   and LiteSpeed Cache plugin.
   Please tell me how I can solve it?

Viewing 5 replies - 1 through 5 (of 5 total)

 *  Plugin Support [qtwrk](https://wordpress.org/support/users/qtwrk/)
 * (@qtwrk)
 * [3 years, 4 months ago](https://wordpress.org/support/topic/php-fatal-error-uncaught-error-call-to-undefined-method-wp_object_cacheflush_/#post-16343506)
 * please provide the report number , you can get it in toolbox -> report -> click“
   send to LiteSpeed” , and also may I know what is your PHP version ?
 *  Thread Starter [Mukesh Patel](https://wordpress.org/support/users/themukeshpatel/)
 * (@themukeshpatel)
 * [3 years, 4 months ago](https://wordpress.org/support/topic/php-fatal-error-uncaught-error-call-to-undefined-method-wp_object_cacheflush_/#post-16343663)
 * I am using PHP 8.1 and here is report number: CKDVAQKC.
    -  This reply was modified 3 years, 4 months ago by [Mukesh Patel](https://wordpress.org/support/users/themukeshpatel/).
 *  Thread Starter [Mukesh Patel](https://wordpress.org/support/users/themukeshpatel/)
 * (@themukeshpatel)
 * [3 years, 4 months ago](https://wordpress.org/support/topic/php-fatal-error-uncaught-error-call-to-undefined-method-wp_object_cacheflush_/#post-16353798)
 * Any update [@qtwrk](https://wordpress.org/support/users/qtwrk/)
 *  [Tynan Beatty](https://wordpress.org/support/users/tynanbe/)
 * (@tynanbe)
 * [3 years, 4 months ago](https://wordpress.org/support/topic/php-fatal-error-uncaught-error-call-to-undefined-method-wp_object_cacheflush_/#post-16356105)
 * Hi [@themukeshpatel](https://wordpress.org/support/users/themukeshpatel/) , please
   feel free to see if this patch resolves the issue for you. [https://github.com/litespeedtech/lscache_wp/pull/517/files](https://github.com/litespeedtech/lscache_wp/pull/517/files)
 *  [usabe](https://wordpress.org/support/users/usabe/)
 * (@usabe)
 * [3 years, 4 months ago](https://wordpress.org/support/topic/php-fatal-error-uncaught-error-call-to-undefined-method-wp_object_cacheflush_/#post-16419566)
 * Due to inactivity of this topic, I will mark this topic as “resolved”. If you
   still have such issues, please feel free to open a ticket with further information
   by emailing to [support@litespeedtech.com](https://wordpress.org/support/topic/php-fatal-error-uncaught-error-call-to-undefined-method-wp_object_cacheflush_/support@litespeedtech.com?output_format=md).
   Remember to reference this topic and ask to assign your ticket to Abe. I will
   check into this further from there.

Viewing 5 replies - 1 through 5 (of 5 total)

The topic ‘PHP Fatal error Uncaught Error: Call to undefined method WP_Object_Cache::
flush_’ is closed to new replies.

 * ![](https://ps.w.org/litespeed-cache/assets/icon-256x256.png?rev=2554181)
 * [LiteSpeed Cache](https://wordpress.org/plugins/litespeed-cache/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/litespeed-cache/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/litespeed-cache/)
 * [Active Topics](https://wordpress.org/support/plugin/litespeed-cache/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/litespeed-cache/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/litespeed-cache/reviews/)

## Tags

 * [fetal error](https://wordpress.org/support/topic-tag/fetal-error/)
 * [redis](https://wordpress.org/support/topic-tag/redis/)
 * [timeout](https://wordpress.org/support/topic-tag/timeout/)

 * 5 replies
 * 4 participants
 * Last reply from: [usabe](https://wordpress.org/support/users/usabe/)
 * Last activity: [3 years, 4 months ago](https://wordpress.org/support/topic/php-fatal-error-uncaught-error-call-to-undefined-method-wp_object_cacheflush_/#post-16419566)
 * Status: resolved