Title: PHP WARNING: Cannot start session when headers already sent
Last modified: October 23, 2019

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# PHP WARNING: Cannot start session when headers already sent

 *  Resolved [tzwick](https://wordpress.org/support/users/tzwick/)
 * (@tzwick)
 * [6 years, 7 months ago](https://wordpress.org/support/topic/php-warning-cannot-start-session-when-headers-already-sent/)
 * Hi!
 * Just a quick feedback. Everything works fine but the PHP error.log is full with
   a PHP warning – like every 20 seconds:
 * child 19551 said into stderr: “NOTICE: PHP message: PHP Warning: session_start():
   Cannot start session when headers already sent in /path/to/host/httpdocs/wp-content/
   plugins/wp-live-chat-support/functions.php on line 4955”
 * OS: Ubuntu Server 18.04.3
    Webserver: Apache 2.4.41 with NGINX (reverse proxy
   mode) PHP: PHP-FPM 7.3.10

Viewing 5 replies - 1 through 5 (of 5 total)

 *  Plugin Author [wordpress3cx](https://wordpress.org/support/users/wordpress3cx/)
 * (@wordpress3cx)
 * [6 years, 7 months ago](https://wordpress.org/support/topic/php-warning-cannot-start-session-when-headers-already-sent/#post-12060919)
 * Thanks for your feedback. We’ll promptly look into this issue.
    Do you have a
   multisite installation?
 *  Thread Starter [tzwick](https://wordpress.org/support/users/tzwick/)
 * (@tzwick)
 * [6 years, 7 months ago](https://wordpress.org/support/topic/php-warning-cannot-start-session-when-headers-already-sent/#post-12061014)
 * No, it`s a single site installation.
 *  Plugin Author [wp3cx](https://wordpress.org/support/users/wp3cx/)
 * (@wp3cx)
 * [6 years, 7 months ago](https://wordpress.org/support/topic/php-warning-cannot-start-session-when-headers-already-sent/#post-12061314)
 * Do you have a sandbox of your site where you can disable all other plugins to
   see if the problem persists? If not, could you provide a list of the plugins 
   you currently have installed?
 *  Thread Starter [tzwick](https://wordpress.org/support/users/tzwick/)
 * (@tzwick)
 * [6 years, 7 months ago](https://wordpress.org/support/topic/php-warning-cannot-start-session-when-headers-already-sent/#post-12065362)
 * Yes, I do.
    It is caused in combination with the Hummingbird-Plugin ( [https://wordpress.org/plugins/hummingbird-performance/](https://wordpress.org/plugins/hummingbird-performance/))
   when “Page Caching” is active. I haven`t tested other cache-plugins.
 *  Plugin Author [wordpress3cx](https://wordpress.org/support/users/wordpress3cx/)
 * (@wordpress3cx)
 * [6 years, 7 months ago](https://wordpress.org/support/topic/php-warning-cannot-start-session-when-headers-already-sent/#post-12071654)
 * Hello [@tzwick](https://wordpress.org/support/users/tzwick/), actually several
   cache plugins interfere with WP Live Chat.
    As you understand, live chat and 
   caching don’t get along very well.
 * In your case, it seems that your website is sending some content before our plugin
   is able to open the session: this is a wrong behavior of some plugin for sure.
   
   We suggest to exclude from caching /wp-live-chat-support directory on your website
   and see if this helps.

Viewing 5 replies - 1 through 5 (of 5 total)

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 * 5 replies
 * 3 participants
 * Last reply from: [wordpress3cx](https://wordpress.org/support/users/wordpress3cx/)
 * Last activity: [6 years, 7 months ago](https://wordpress.org/support/topic/php-warning-cannot-start-session-when-headers-already-sent/#post-12071654)
 * Status: resolved