Title: error when actvie Autoptimize : Last modified: August 16, 2023 --- # error when actvie Autoptimize : * Resolved [activelife.vn](https://wordpress.org/support/users/activelifevn/) * (@activelifevn) * [2 years, 9 months ago](https://wordpress.org/support/topic/error-when-actvie-autoptimize/) * **Fatal error**: Unknown: Cannot use output buffering in output buffering display handlers in **Unknown** on line **0** * when I active Autoptimize, my web error, and disble it, my web is ok. Can u help me. ? * suggest me which keyword to fix it Viewing 15 replies - 1 through 15 (of 25 total) 1 [2](https://wordpress.org/support/topic/error-when-actvie-autoptimize/page/2/?output_format=md) [→](https://wordpress.org/support/topic/error-when-actvie-autoptimize/page/2/?output_format=md) * Plugin Author [Optimizing Matters](https://wordpress.org/support/users/optimizingmatters/) * (@optimizingmatters) * [2 years, 9 months ago](https://wordpress.org/support/topic/error-when-actvie-autoptimize/#post-16976324) * looks like a conflict with another plugin I’m afraid, if you want to troubleshoot disable plugins one by one and try enabling autoptimize each time before re-enabling the plugin. if not plugin it *could* also be the theme, so switching to a default theme (twenty twenty-tree) might also help. * hope this helps, frank * Thread Starter [activelife.vn](https://wordpress.org/support/users/activelifevn/) * (@activelifevn) * [2 years, 9 months ago](https://wordpress.org/support/topic/error-when-actvie-autoptimize/#post-16976357) * I will try and get back to you. thank you - This reply was modified 2 years, 9 months ago by [activelife.vn](https://wordpress.org/support/users/activelifevn/). * Thread Starter [activelife.vn](https://wordpress.org/support/users/activelifevn/) * (@activelifevn) * [2 years, 9 months ago](https://wordpress.org/support/topic/error-when-actvie-autoptimize/#post-16976464) * elementor , when I disable it, everything is ok . Can u suggest for me. thank you so much. * Thread Starter [activelife.vn](https://wordpress.org/support/users/activelifevn/) * (@activelifevn) * [2 years, 9 months ago](https://wordpress.org/support/topic/error-when-actvie-autoptimize/#post-16976490) * update: when I disable elementor pro and active element and Autoptimize, it’s ok. I think it conflict elementor pro. thanks * Plugin Author [Optimizing Matters](https://wordpress.org/support/users/optimizingmatters/) * (@optimizingmatters) * [2 years, 9 months ago](https://wordpress.org/support/topic/error-when-actvie-autoptimize/#post-16976498) * so if Autoptimize is active, do things work if: 1. elementor pro is off but “ active element” is on? 2. elementor pro is on but “active element” is off? 3. elementor pro is off and “active element” is also off? * frank * Thread Starter [activelife.vn](https://wordpress.org/support/users/activelifevn/) * (@activelifevn) * [2 years, 9 months ago](https://wordpress.org/support/topic/error-when-actvie-autoptimize/#post-16976513) * yes, * Plugin Author [Optimizing Matters](https://wordpress.org/support/users/optimizingmatters/) * (@optimizingmatters) * [2 years, 9 months ago](https://wordpress.org/support/topic/error-when-actvie-autoptimize/#post-16976519) * yes for all 3? so you can keep “elementor pro” on and disable “active element” and it works? * Thread Starter [activelife.vn](https://wordpress.org/support/users/activelifevn/) * (@activelifevn) * [2 years, 9 months ago](https://wordpress.org/support/topic/error-when-actvie-autoptimize/#post-16976527) * Exactly * Plugin Author [Optimizing Matters](https://wordpress.org/support/users/optimizingmatters/) * (@optimizingmatters) * [2 years, 9 months ago](https://wordpress.org/support/topic/error-when-actvie-autoptimize/#post-16976543) * and what is “active element”? * Thread Starter [activelife.vn](https://wordpress.org/support/users/activelifevn/) * (@activelifevn) * [2 years, 9 months ago](https://wordpress.org/support/topic/error-when-actvie-autoptimize/#post-16976551) * before that i update php to Version 8.0.30.. * Thread Starter [activelife.vn](https://wordpress.org/support/users/activelifevn/) * (@activelifevn) * [2 years, 9 months ago](https://wordpress.org/support/topic/error-when-actvie-autoptimize/#post-16976555) * now, I off element pro. just element and Autoptimize. it’s ok with me, but I don’t why . * do you think I need remove elementor pro and reinstall - This reply was modified 2 years, 9 months ago by [activelife.vn](https://wordpress.org/support/users/activelifevn/). * Plugin Author [Optimizing Matters](https://wordpress.org/support/users/optimizingmatters/) * (@optimizingmatters) * [2 years, 9 months ago](https://wordpress.org/support/topic/error-when-actvie-autoptimize/#post-16976624) * PHP version for AO’s point of view is not (or should not be) a problem. * ah, so it’s “elementor pro” and “elementor” instead of “active element”? * so re. “elementor pro”; what version are you using and when was that released? * Thread Starter [activelife.vn](https://wordpress.org/support/users/activelifevn/) * (@activelifevn) * [2 years, 9 months ago](https://wordpress.org/support/topic/error-when-actvie-autoptimize/#post-16976638) * verision 3.15.0 and it is new update. .. elementor pro and elementor.   * Plugin Author [Optimizing Matters](https://wordpress.org/support/users/optimizingmatters/) * (@optimizingmatters) * [2 years, 9 months ago](https://wordpress.org/support/topic/error-when-actvie-autoptimize/#post-16976662) * OK, so: 1. do you get the error on all pages of your site? 2. do you also get the error on a (test) page that was not created with Elementor (so a “normal” wordpress page/ post)? 3. do you also get the error when all options in Autoptimize( JS, CSS, HTML optimization) are off? 4. do you see any relevant information in the PHP error logfile? * Plugin Author [Optimizing Matters](https://wordpress.org/support/users/optimizingmatters/) * (@optimizingmatters) * [2 years, 9 months ago](https://wordpress.org/support/topic/error-when-actvie-autoptimize/#post-16976820) * additionally; does the error happen when logged in, or also when logged out? Viewing 15 replies - 1 through 15 (of 25 total) 1 [2](https://wordpress.org/support/topic/error-when-actvie-autoptimize/page/2/?output_format=md) [→](https://wordpress.org/support/topic/error-when-actvie-autoptimize/page/2/?output_format=md) The topic ‘error when actvie Autoptimize :’ is closed to new replies. * ![](https://ps.w.org/autoptimize/assets/icon-256X256.png?rev=2211608) * [Autoptimize](https://wordpress.org/plugins/autoptimize/) * [Frequently Asked Questions](https://wordpress.org/plugins/autoptimize/#faq) * [Support Threads](https://wordpress.org/support/plugin/autoptimize/) * [Active Topics](https://wordpress.org/support/plugin/autoptimize/active/) * [Unresolved Topics](https://wordpress.org/support/plugin/autoptimize/unresolved/) * [Reviews](https://wordpress.org/support/plugin/autoptimize/reviews/) * 25 replies * 2 participants * Last reply from: [activelife.vn](https://wordpress.org/support/users/activelifevn/) * Last activity: [2 years, 9 months ago](https://wordpress.org/support/topic/error-when-actvie-autoptimize/page/2/#post-17003674) * Status: resolved