Title: FATAL ERROR
Last modified: July 17, 2017

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# FATAL ERROR

 *  [vividtreks](https://wordpress.org/support/users/vividtreks/)
 * (@vividtreks)
 * [8 years, 9 months ago](https://wordpress.org/support/topic/fatal-error-2608/)
 * I’m currently on ver. 4.8 and I’m trying to use the WP Super Cache Plugin. Whenever
   I turn the caching function on, I keep getting:
 * Fatal error: Unknown: Cannot use output buffering in output buffering display
   handlers in Unknown on line 0
 * I’m aware that there’s another thread for this same issue but it says it shouldn’t
   show up on the newest version of WP yet I’m still getting the issue. I don’t 
   believe I have any conflicting plugins as I’ve tried deactivating the other plugins
   while leaving the Cache plugin on.

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

 *  [Ben](https://wordpress.org/support/users/benbornschein/)
 * (@benbornschein)
 * [8 years, 8 months ago](https://wordpress.org/support/topic/fatal-error-2608/#post-9332312)
 * After you disabled the other plugins, did you refreshed the cache in WP Super
   Cache?
 *  Thread Starter [vividtreks](https://wordpress.org/support/users/vividtreks/)
 * (@vividtreks)
 * [8 years, 8 months ago](https://wordpress.org/support/topic/fatal-error-2608/#post-9333589)
 * I sure did. I’ve since tried 2 different cache programs and neither one of them
   acts up in the same way as WP Super Cache.
 *  [bluebearmedia](https://wordpress.org/support/users/bluebearmedia/)
 * (@bluebearmedia)
 * [8 years, 8 months ago](https://wordpress.org/support/topic/fatal-error-2608/#post-9334259)
 * I have the exact same issue…
 * This is showing in the error log:
 * [19-Jul-2017 15:57:44 UTC] PHP Warning: array_map() expects parameter 1 to be
   a valid callback, function ‘mb_strtolower’ not found or invalid function name
   in /home/bbmedia/public_html/w/wp-content/plugins/wp-super-cache/wp-cache-phase2.
   php on line 236
    [19-Jul-2017 15:57:44 UTC] PHP Fatal error: Call to undefined
   function mb_strtolower() in /home/bbmedia/public_html/w/wp-content/plugins/wp-
   super-cache/wp-cache-phase2.php on line 255 [19-Jul-2017 15:57:44 UTC] PHP Fatal
   error: Unknown: Cannot use output buffering in output buffering display handlers
   in Unknown on line 0
 * Reverting back to the previous version (WP Super Cache 1.4.9) corrected the issue
   for me…
    -  This reply was modified 8 years, 8 months ago by [bluebearmedia](https://wordpress.org/support/users/bluebearmedia/).

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

The topic ‘FATAL ERROR’ is closed to new replies.

 * ![](https://ps.w.org/wp-super-cache/assets/icon-256x256.png?rev=1095422)
 * [WP Super Cache](https://wordpress.org/plugins/wp-super-cache/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/wp-super-cache/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/wp-super-cache/)
 * [Active Topics](https://wordpress.org/support/plugin/wp-super-cache/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/wp-super-cache/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/wp-super-cache/reviews/)

 * 3 replies
 * 3 participants
 * Last reply from: [bluebearmedia](https://wordpress.org/support/users/bluebearmedia/)
 * Last activity: [8 years, 8 months ago](https://wordpress.org/support/topic/fatal-error-2608/#post-9334259)
 * Status: not resolved