Title: Synchronous XMLHttpRequest console error
Last modified: August 31, 2016

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# Synchronous XMLHttpRequest console error

 *  Resolved [emjay_dee](https://wordpress.org/support/users/emjay_dee/)
 * (@emjay_dee)
 * [10 years, 1 month ago](https://wordpress.org/support/topic/synchronous-xmlhttprequest-console-error/)
 * I’m getting a console error “Synchronous XMLHttpRequest on the main thread is
   deprecated because of its detrimental effects to the end user’s experience. For
   more help, check [https://xhr.spec.whatwg.org/.&#8221](https://xhr.spec.whatwg.org/.&#8221);
 * Is there a fix for that?
 * thanks
 * [https://wordpress.org/plugins/autoptimize/](https://wordpress.org/plugins/autoptimize/)

Viewing 3 replies - 1 through 3 (of 3 total)

 *  Thread Starter [emjay_dee](https://wordpress.org/support/users/emjay_dee/)
 * (@emjay_dee)
 * [10 years, 1 month ago](https://wordpress.org/support/topic/synchronous-xmlhttprequest-console-error/#post-7257251)
 * /wp-content/cache/autoptimize/js/autoptimize_a49f691f6962bfb35ef1135cde918cab.
   js
 * line 3
 *  Plugin Author [Frank Goossens](https://wordpress.org/support/users/futtta/)
 * (@futtta)
 * [10 years, 1 month ago](https://wordpress.org/support/topic/synchronous-xmlhttprequest-console-error/#post-7257268)
 * Autoptimize by and off itself does not add any javascript emjay_dee, it merely
   aggregates the JS that plugins and your theme add to your site so there’s no 
   fix in AO.
 * What you can do; reload your page with ?ao_noptimize=1 added to the URL and look
   for the same message on the console, which at that point help you identify the
   plugin (or theme) which added that synchronous xhr-request in the first place.
   And then you can contact the author to ask them if that could be changed?
 * hope this clarifies,
    frank
 *  Thread Starter [emjay_dee](https://wordpress.org/support/users/emjay_dee/)
 * (@emjay_dee)
 * [10 years, 1 month ago](https://wordpress.org/support/topic/synchronous-xmlhttprequest-console-error/#post-7257381)
 * Thank you for this. The problem was with an old version of jquery and it was 
   solved by updating to the latest WordPress.

Viewing 3 replies - 1 through 3 (of 3 total)

The topic ‘Synchronous XMLHttpRequest console error’ is closed to new replies.

 * ![](https://ps.w.org/autoptimize/assets/icon-256X256.png?rev=2211608)
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## Tags

 * [deprecated](https://wordpress.org/support/topic-tag/deprecated/)
 * [synchronous](https://wordpress.org/support/topic-tag/synchronous/)
 * [XMLHttpRequest](https://wordpress.org/support/topic-tag/xmlhttprequest/)

 * 3 replies
 * 2 participants
 * Last reply from: [emjay_dee](https://wordpress.org/support/users/emjay_dee/)
 * Last activity: [10 years, 1 month ago](https://wordpress.org/support/topic/synchronous-xmlhttprequest-console-error/#post-7257381)
 * Status: resolved