Wordpress LScache Plugin: PHP Fatal error: Class LiteSpeed_Cache_ESI not found
Last Updated on: Wed, 15 Apr 2026 00:00:02 Im getting this on all sites that I have Litespeed installed on: Stack trace: #0 [internal function]: LiteSpeed_Cache->send_headers_force( , 9) #1 main thrown in /home/talented1/public_html/site/wp-content/plugins/litespeed-cache/inc/litespeed-cache.class.php on line 476 [23-Oct-2018 13:24:29 UTC] PHP Fatal error: Class LiteSpeed_Cache_Tag not found in /home/talented1/public_html/site/wp-content/plugins/litespeed-cache/inc/cdn.class.php on line 468 [23-Oct-2018 13:24:29 UTC] PHP Fatal error: Uncaught Error: Class LiteSpeed_Cache_CDN not found in /home/talented1/public_html/site/wp-content/plugins/litespeed-cache/inc/litespeed-cache.class.php:487 Stack trace: #0 [internal function]: LiteSpeed_Cache->send_headers_force( , 9) #1 main thrown in /home/talented1/public_html/site/wp-content/plugins/litespeed-cache/inc/litespeed-cache.class.php on line 487 [23-Oct-2018 13:25:59 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/advanced-custom-fields-pro/includes/fields/class-acf-field-select.php on line 481 [23-Oct-2018 13:25:59 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [23-Oct-2018 13:34:57 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/wordpress-seo/frontend/class-opengraph.php on line 209 [23-Oct-2018 13:34:57 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [23-Oct-2018 15:19:58 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/litespeed-cache/inc/gui.class.php on line 124 [23-Oct-2018 15:19:58 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [23-Oct-2018 17:08:19 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/advanced-custom-fields-pro/pro/fields/class-acf-field-flexible-content.php on line 397 [23-Oct-2018 17:08:19 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [23-Oct-2018 17:28:20 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/advanced-custom-fields-pro/pro/fields/class-acf-field-clone.php on line 871 [23-Oct-2018 17:28:20 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [23-Oct-2018 21:30:07 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/advanced-custom-fields-pro/includes/fields/class-acf-field-number.php on line 128 [23-Oct-2018 21:30:07 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [23-Oct-2018 23:40:50 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/optinmonster/OMAPI/Rules.php on line 625 [23-Oct-2018 23:40:50 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [24-Oct-2018 02:45:19 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/wordpress-seo/inc/sitemaps/class-taxonomy-sitemap-provider.php on line 196 [24-Oct-2018 02:45:19 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [24-Oct-2018 03:52:45 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/litespeed-cache/inc/css.cls.php on line 149 [24-Oct-2018 03:52:45 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [24-Oct-2018 07:14:37 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/advanced-custom-fields-pro/includes/fields/class-acf-field-user.php on line 422 [24-Oct-2018 07:14:37 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [24-Oct-2018 10:49:16 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/advanced-custom-fields-pro/pro/fields/class-acf-field-flexible-content.php on line 526 [24-Oct-2018 10:49:16 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [24-Oct-2018 12:38:11 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/wordpress-seo/frontend/class-twitter.php on line 656 [24-Oct-2018 12:38:12 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [24-Oct-2018 13:03:34 UTC] PHP Fatal error: Class LiteSpeed_Cache_Control not found in /home/talented1/public_html/site/wp-content/plugins/litespeed-cache/inc/optimize.class.php on line 174 [24-Oct-2018 13:03:35 UTC] PHP Fatal error: Uncaught Error: Class LiteSpeed_Cache_Optimize not found in /home/talented1/public_html/site/wp-content/plugins/litespeed-cache/inc/litespeed-cache.class.php:485 Stack trace: #0 [internal function]: LiteSpeed_Cache->send_headers_force( , 9) #1 main thrown in /home/talented1/public_html/site/wp-content/plugins/litespeed-cache/inc/litespeed-cache.class.php on line 485 [24-Oct-2018 14:01:40 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/wordpress-seo/frontend/class-frontend.php on line 1177 [24-Oct-2018 14:01:40 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 Hi @greencode, Can you share a report number with us? The report is found in WP Admin > LiteSpeed Cache > Report. Press the Send to LiteSpeed button, and let us know what the generated Report Number is. Thanks, Stanley Hi. I think this sent Report number: IZCCZKQK I also use Advanced Custom Fields and it gives me the same error, I do not think it necessary to open a new post explaining the same Report number: DVBQIKQU Report date: 10/29/2018 02:47:52 Thanks, @greencode and @esteban88, we are checking on this issue now, will get you back soon. Hi @greencode and @esteban88, May I know is this issue happening when just activated ACF-pro and Litespeed? As we cannot reproduce the error, is it possible for us to access the problem site or clone another environment for testing? You can join our Slack channel or submit a ticket here for passing us the details. Thanks, Stanley Hi. Heres my list of errors for the past few days. As you can see its not just ACF. Its Yoast SEO and Wordfence. Ive not been activating or deactivating any plugins. These plugins have been on the site for a number of months. [28-Oct-2018 00:55:42 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/wordpress-seo/inc/class-wpseo-replace-vars.php on line 749 [28-Oct-2018 00:55:43 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [28-Oct-2018 05:25:50 UTC] PHP Warning: Illegal offset type in /home/talented1/public_html/site/wp-includes/class-wp-hook.php on line 277 [28-Oct-2018 05:25:50 UTC] PHP Warning: Invalid argument supplied for foreach() in /home/talented1/public_html/site/wp-includes/class-wp-hook.php on line 277 [28-Oct-2018 10:35:49 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/advanced-custom-fields-pro/includes/fields/class-acf-field-number.php on line 92 [28-Oct-2018 10:35:50 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [28-Oct-2018 10:35:50 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/advanced-custom-fields-pro/includes/fields/class-acf-field-radio.php on line 156 [28-Oct-2018 10:35:50 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [28-Oct-2018 10:35:50 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/advanced-custom-fields-pro/includes/fields/class-acf-field-post_object.php on line 38 [28-Oct-2018 10:35:50 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [28-Oct-2018 11:53:34 UTC] PHP Fatal error: Uncaught OutOfBoundsException: ipRange is not a valid property for this block type in /home/talented1/public_html/site/wp-content/plugins/wordfence/models/block/wfBlock.php:1148 Stack trace: #0 /home/talented1/public_html/site/wp-content/plugins/wordfence/waf/wfWAFIPBlocksController.php(63): wfBlock->__get(ipRange) #1 [internal function]: wfWAFIPBlocksController::synchronizeConfigSettings() #2 main thrown in /home/talented1/public_html/site/wp-content/plugins/wordfence/models/block/wfBlock.php on line 1148 [28-Oct-2018 13:01:33 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/advanced-custom-fields-pro/includes/fields/class-acf-field-number.php on line 25 [28-Oct-2018 13:01:33 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [28-Oct-2018 17:48:14 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/wordpress-seo/frontend/class-opengraph-image.php on line 517 [28-Oct-2018 17:48:15 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [28-Oct-2018 18:09:29 UTC] PHP Fatal error: Uncaught OutOfBoundsException: ipRange is not a valid property for this block type in /home/talented1/public_html/site/wp-content/plugins/wordfence/models/block/wfBlock.php:1148 Stack trace: #0 /home/talented1/public_html/site/wp-content/plugins/wordfence/waf/wfWAFIPBlocksController.php(63): wfBlock->__get(ipRange) #1 [internal function]: wfWAFIPBlocksController::synchronizeConfigSettings() #2 main thrown in /home/talented1/public_html/site/wp-content/plugins/wordfence/models/block/wfBlock.php on line 1148 [28-Oct-2018 23:06:01 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/advanced-custom-fields-pro/includes/fields/class-acf-field-post_object.php on line 570 [28-Oct-2018 23:06:01 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [29-Oct-2018 01:22:13 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/advanced-custom-fields-pro/pro/fields/class-acf-field-flexible-content.php on line 417 [29-Oct-2018 01:22:13 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [29-Oct-2018 02:43:49 UTC] PHP Fatal error: Class LiteSpeed_Cache_Admin_Rules not found in /home/talented1/public_html/site/wp-content/plugins/litespeed-cache/admin/litespeed-cache-admin-rules.class.php on line 472 [29-Oct-2018 03:40:51 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/wordpress-seo/frontend/class-opengraph.php on line 550 [29-Oct-2018 03:40:51 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [29-Oct-2018 03:47:56 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/wordpress-seo/frontend/class-opengraph-image.php on line 93 [29-Oct-2018 03:47:56 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [29-Oct-2018 07:10:41 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/advanced-custom-fields-pro/includes/fields/class-acf-field-image.php on line 134 [29-Oct-2018 07:10:41 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [29-Oct-2018 07:37:06 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/advanced-custom-fields-pro/pro/fields/class-acf-field-flexible-content.php on line 306 [29-Oct-2018 07:37:06 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [29-Oct-2018 10:47:42 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/advanced-custom-fields-pro/includes/fields/class-acf-field-wysiwyg.php on line 330 [29-Oct-2018 10:47:42 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 [29-Oct-2018 11:35:08 UTC] PHP Fatal error: Class LiteSpeed_Cache_ESI not found in /home/talented1/public_html/site/wp-content/plugins/advanced-custom-fields-pro/includes/fields/class-acf-field-image.php on line 134 [29-Oct-2018 11:35:08 UTC] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0 Hi @greencode, Please join our Slack channel or submit a ticket here for discussion. Thanks, Stanley ]
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