Wordpress LScache Plugin: LiteSpeed Cache Image Optimisation ? failed to decode post json
Last Updated on: Wed, 15 Apr 2026 00:00:02 Hi, Recently installed LiteSpeed Web Server and subsequently installed LiteSpeed Cache plugins on all relevant WordPress installations via WHM admin > LiteSpeed Web Server. Im having a problem with Image Optimisation on one of the sites. The output log for the issue starts with this error: [IAPI] failed to decode post json: hash does not match: ClientCB followed by a chunk of HTML code outputting this error: Sorry, there was an error. Please be sure JavaScript and Cookies are enabled in your browser and try again The full section of the output log error is 04/08/20 01:02:18.804 [82.71.48.123:59617 1 TyK] [IAPI] failed to decode post json: hash does not match: ClientCB 04/08/20 01:02:18.832 [82.71.48.123:59617 1 TyK] [IAPI] request key failed: 04/08/20 01:02:18.836 [82.71.48.123:59617 1 TyK] [IAPI] posting to : https://eu.wp.api.litespeedtech.com/media_sync_data 04/08/20 01:02:18.876 [82.71.48.123:59617 1 TyK] [IAPI] failed to decode post json: no auth_key 04/08/20 01:02:18.885 [82.71.48.123:59617 1 TyK] [Ctrl] 301 from https://www.gbstampline.com/wp-admin/admin.php 04/08/20 01:02:18.885 [82.71.48.123:59617 1 TyK] [Ctrl] 301 to https://www.gbstampline.com/wp-admin/admin.php?page=lscache-optimization&type=sync_data 04/08/20 01:02:18.885 [82.71.48.123:59617 1 TyK] [Ctrl] X Cache_control -> no Cache ( 301 to same url ) 04/08/20 01:02:18.886 [82.71.48.123:59617 1 TyK] [Ctrl] not cacheable before ctrl finalize 04/08/20 01:02:18.886 [82.71.48.123:59617 1 TyK] [Router] get_uid: 1106 04/08/20 01:02:18.886 [82.71.48.123:59617 1 TyK] [Router] get_role: administrator 04/08/20 01:02:18.887 [82.71.48.123:59617 1 TyK] X-LiteSpeed-Cache-Control: no-cache 04/08/20 01:02:18.887 [82.71.48.123:59617 1 TyK] [Optm] bypass: Not frontend HTML type 04/08/20 01:02:18.887 [82.71.48.123:59617 1 TyK] End response I get the same failed to decode json error when trying to send the report to LiteSpeed Report number: WXSHLWHJ Report date: 04/08/2020 14:19:01 Hi, This usually happens when you have some kind of protective plugins that checks incoming traffic which in this , image server callback are not exactly a normal browser request , so it got stopped and inspected ,therefore hit error from the log message, whatever this plugin is , it requires javascript and cookie to perform the check. Please try disable these kind of plugins or add our IPs into its whitelist Best regards, RESOLVED I have resolved this issue. It appears that WP SpamShield was conflicting with the LiteSpeed Cache plugin. Glad to know you solved it
LiteCache Rush: Speed comes from using less, not from doing it faster
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