Title: Optimize Javascript causes issues
Last modified: April 30, 2019

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# Optimize Javascript causes issues

 *  Resolved [harveyl12](https://wordpress.org/support/users/harveyl12/)
 * (@harveyl12)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/optimize-javascript-causes-issues/)
 * Hi,
 * I am using the Autoptimize plugin and have been for years.
 * After doing some WordPress updates and plugin updates I have came across an issue
   with the Autoptimize plugin…
 * When having the **Optimise JavaScript Code?** setting enabled it caused pages
   to load saying _Fatal error: Unknown: Cannot use output buffering in output buffering
   display handlers in Unknown on line 0_
 * You can see this issue by going to this site **testing.camerabeanbags.co.uk**
   as I have had to disable this setting on the live site so customers don’t see
   the error.
 * When this error message shows on the page, it will show on page but then if you
   refresh the page then it will load the page fine with no error message. However
   this is only per browser/pc and when the caches are cleared the error will show
   again.
 * Not sure why it is happening but I never used to have trouble, again it is the
   javacript optimization setting that seems to be causing this.
 * Thanks,
 * Harvey
 * The page I need help with: _[[log in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Foptimize-javascript-causes-issues%2F%3Foutput_format%3Dmd&locale=en_US)
   to see the link]_

Viewing 1 replies (of 1 total)

 *  Plugin Author [Optimizing Matters](https://wordpress.org/support/users/optimizingmatters/)
 * (@optimizingmatters)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/optimize-javascript-causes-issues/#post-11483657)
 * that’s because you seem to have another plugin active that also does JS (and 
   CSS) optimization, combining multiple such plugins can indeed cause issues like
   these. disable the minification in other plugins and all should work.
 * hope this helps,
    frank

Viewing 1 replies (of 1 total)

The topic ‘Optimize Javascript causes issues’ 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/)

## Tags

 * [fatal error](https://wordpress.org/support/topic-tag/fatal-error/)
 * [javascript](https://wordpress.org/support/topic-tag/javascript/)
 * [optimization](https://wordpress.org/support/topic-tag/optimization/)
 * [page won't load](https://wordpress.org/support/topic-tag/page-wont-load/)

 * 1 reply
 * 2 participants
 * Last reply from: [Optimizing Matters](https://wordpress.org/support/users/optimizingmatters/)
 * Last activity: [6 years, 11 months ago](https://wordpress.org/support/topic/optimize-javascript-causes-issues/#post-11483657)
 * Status: resolved