Title: W3_Plugin_TotalCache::ob_callback() expected to be a reference
Last modified: August 30, 2016

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# W3_Plugin_TotalCache::ob_callback() expected to be a reference

 *  [Rolf Allard van Hagen](https://wordpress.org/support/users/ravanh/)
 * (@ravanh)
 * [10 years, 11 months ago](https://wordpress.org/support/topic/w3_plugin_totalcacheob_callback-expected-to-be-a-reference/)
 * Many, many entries bloating the hhvm/error.log file:
 *     ```
       Warning: Parameter 1 to W3_Plugin_TotalCache::ob_callback() expected to be a reference, value given in /var/www/xxxx.xx/htdocs/wp-includes/functions.php on line 3282
       ```
   
 * I have only Database and Object Cache enabled and set to Memcached.
 * [https://wordpress.org/plugins/w3-total-cache/](https://wordpress.org/plugins/w3-total-cache/)

Viewing 6 replies - 1 through 6 (of 6 total)

 *  [bemeall](https://wordpress.org/support/users/bemeall/)
 * (@bemeall)
 * [10 years, 7 months ago](https://wordpress.org/support/topic/w3_plugin_totalcacheob_callback-expected-to-be-a-reference/#post-6314305)
 * Also having this error filling the logs on HHVM.
 * Seems that it’s not that difficult to fix, according to this thread: [https://wordpress.org/support/topic/warning-with-hhvm?replies=19](https://wordpress.org/support/topic/warning-with-hhvm?replies=19)
 * But it is not fixed in the current version, is it?
 *  [Umbrovskis.com](https://wordpress.org/support/users/rolandinsh/)
 * (@rolandinsh)
 * [10 years, 1 month ago](https://wordpress.org/support/topic/w3_plugin_totalcacheob_callback-expected-to-be-a-reference/#post-6314321)
 * Same with PHP 7.0 (Ubuntu 16.04 / Apache2.4 behind NGINX)
 *  [Umbrovskis.com](https://wordpress.org/support/users/rolandinsh/)
 * (@rolandinsh)
 * [10 years, 1 month ago](https://wordpress.org/support/topic/w3_plugin_totalcacheob_callback-expected-to-be-a-reference/#post-6314322)
 * btw, solution is here: [[resolved] Should I be worried? Warning: Parameter 1 to W3_Plugin_TotalCache::ob_callback()](https://wordpress.org/support/topic/should-i-be-worried-warning-parameter-1-to-w3_plugin_totalcacheob_callback?replies=8#post-7981181),
 * but that is manual workaround 😐
 *  [Melroy](https://wordpress.org/support/users/danger89/)
 * (@danger89)
 * [10 years ago](https://wordpress.org/support/topic/w3_plugin_totalcacheob_callback-expected-to-be-a-reference/#post-6314323)
 * Same issue using PHP 7.
 *  [prateekvarma](https://wordpress.org/support/users/prateekvarma/)
 * (@prateekvarma)
 * [10 years ago](https://wordpress.org/support/topic/w3_plugin_totalcacheob_callback-expected-to-be-a-reference/#post-6314324)
 * I had the same error. The solution is very simple actually.. You just need to
   remove the & character –
    [http://webhostingground.com/t/how-to-fix-w3-total-cache-error-on-wordpress](http://webhostingground.com/t/how-to-fix-w3-total-cache-error-on-wordpress)
 *  [Gwyneth Llewelyn](https://wordpress.org/support/users/gwynethllewelyn/)
 * (@gwynethllewelyn)
 * [10 years ago](https://wordpress.org/support/topic/w3_plugin_totalcacheob_callback-expected-to-be-a-reference/#post-6314325)
 * Although that fix certainly made the warning message disappear, I wonder if W3TC
   is working at all under PHP 7. I’m just asking, because those ob_callbacks() 
   are very likely the glue that is behind the whole page capture and saving to 
   memory or disk; in my case, I have noticed that W3TC simply refuses to write 
   anything to disk. Ever again. Silly me, I had stale files lying around in those
   cache directories, from before the upgrade to PHP 7, and now, as far as I can
   see, they are not deleted, nor overwritten. Nothing. I can even delete the whole
   directory structure and W3TC will not write it again, ever.
 * It might be just my configuration, though.

Viewing 6 replies - 1 through 6 (of 6 total)

The topic ‘W3_Plugin_TotalCache::ob_callback() expected to be a reference’ is closed
to new replies.

 * ![](https://ps.w.org/w3-total-cache/assets/icon-256x256.png?rev=1041806)
 * [W3 Total Cache](https://wordpress.org/plugins/w3-total-cache/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/w3-total-cache/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/w3-total-cache/)
 * [Active Topics](https://wordpress.org/support/plugin/w3-total-cache/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/w3-total-cache/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/w3-total-cache/reviews/)

 * 6 replies
 * 6 participants
 * Last reply from: [Gwyneth Llewelyn](https://wordpress.org/support/users/gwynethllewelyn/)
 * Last activity: [10 years ago](https://wordpress.org/support/topic/w3_plugin_totalcacheob_callback-expected-to-be-a-reference/#post-6314325)
 * Status: not resolved