Title: multisite error (Warning: Cannot modify header information) Last modified: August 21, 2016 --- # multisite error (Warning: Cannot modify header information) * Resolved [shoopiable](https://wordpress.org/support/users/shoopiable/) * (@shoopiable) * [11 years, 10 months ago](https://wordpress.org/support/topic/multisite-error-warning-cannot-modify-header-information/) * well done on getting the update out! * I was attempting to get the multisite configuration going and came across the following warning error on a fresh install. * Create a multisite environment * Multisite * Main site – user1 * subsite2 – user2 * subsite3 – user3 * I have your plugin installed on each of the two subsites (not network enabled) * It correctly restricts access to the subsites that a user is not logged into, but when a logged in users attempts to visit a subsite which they don’t have an account registered for, it spits out a header error (see below the output). So in the above example, user2 logs into subsite2 correctly, but then attempts to navigate to subsite3, this is when the warning appears. * I’ve installed this on a fresh multisite so no plugin conflicts are possible. the only thing I can think of is a theme incompatibility. * I would be happy to help co-ordinate the debugging with you if you like or even give you access to my setup if you like.. * Warning: Cannot modify header information – headers already sent by (output started at /www/ms/wp-content/plugins/jonradio-private-site/includes/public.php:183) in /www/ms/wp-includes/pluggable.php on line 883 * Warning: Cannot modify header information – headers already sent by (output started at /www/ms/wp-content/plugins/jonradio-private-site/includes/public.php:183) in /www/ms/wp-includes/pluggable.php on line 884 * Warning: Cannot modify header information – headers already sent by (output started at /www/ms/wp-content/plugins/jonradio-private-site/includes/public.php:183) in /www/ms/wp-includes/pluggable.php on line 885 * Warning: Cannot modify header information – headers already sent by (output started at /www/ms/wp-content/plugins/jonradio-private-site/includes/public.php:183) in /www/ms/wp-includes/pluggable.php on line 886 * Warning: Cannot modify header information – headers already sent by (output started at /www/ms/wp-content/plugins/jonradio-private-site/includes/public.php:183) in /www/ms/wp-includes/pluggable.php on line 887 * Warning: Cannot modify header information – headers already sent by (output started at www/ms/wp-content/plugins/jonradio-private-site/includes/public.php:183) in/ www/ms/wp-includes/pluggable.php on line 888 * Warning: Cannot modify header information – headers already sent by (output started at o/www/ms/wp-content/plugins/jonradio-private-site/includes/public.php:183) in /www/ms/wp-includes/pluggable.php on line 891 * Warning: Cannot modify header information – headers already sent by (output started at /www/ms/wp-content/plugins/jonradio-private-site/includes/public.php:183) in /www/ms/wp-includes/pluggable.php on line 892 * Warning: Cannot modify header information – headers already sent by (output started at /www/ms/wp-content/plugins/jonradio-private-site/includes/public.php:183) in /www/ms/wp-includes/pluggable.php on line 893 * Warning: Cannot modify header information – headers already sent by (output started at /www/ms/wp-content/plugins/jonradio-private-site/includes/public.php:183) in /www/ms/wp-includes/pluggable.php on line 894 * Warning: Cannot modify header information – headers already sent by (output started at /www/ms/wp-content/plugins/jonradio-private-site/includes/public.php:183) in /www/ms/wp-includes/pluggable.php on line 897 * Warning: Cannot modify header information – headers already sent by (output started at /www/ms/wp-content/plugins/jonradio-private-site/includes/public.php:183) in /www/ms/wp-includes/pluggable.php on line 898 * Warning: Cannot modify header information – headers already sent by (output started at /www/ms/wp-content/plugins/jonradio-private-site/includes/public.php:183) in /www/ms/wp-includes/pluggable.php on line 899 * Warning: Cannot modify header information – headers already sent by (output started at /www/ms/wp-content/plugins/jonradio-private-site/includes/public.php:183) in /www/ms/wp-includes/pluggable.php on line 900 Your User ID has not been defined to this Site. If you believe that you should be able to access this Site, please contact your network administrator or this site’s webmaster, and mention that your access was blocked by the jonradio Private Site plugin. * [https://wordpress.org/plugins/jonradio-private-site/](https://wordpress.org/plugins/jonradio-private-site/) Viewing 7 replies - 1 through 7 (of 7 total) * [jon](https://wordpress.org/support/users/adiant/) * (@adiant) * [11 years, 10 months ago](https://wordpress.org/support/topic/multisite-error-warning-cannot-modify-header-information/#post-5073870) * I will immediately try and re-create the error on my test system. Then I’ll know how to proceed. * Thanks for reporting this so quickly. * Thread Starter [shoopiable](https://wordpress.org/support/users/shoopiable/) * (@shoopiable) * [11 years, 10 months ago](https://wordpress.org/support/topic/multisite-error-warning-cannot-modify-header-information/#post-5073873) * great, thank you for getting to this stuff in such a timely manner! * [jon](https://wordpress.org/support/users/adiant/) * (@adiant) * [11 years, 10 months ago](https://wordpress.org/support/topic/multisite-error-warning-cannot-modify-header-information/#post-5073876) * I need to do more testing as my first attempt did not re-create your problem, which appears to be a looping issue related to my use of wp_logout() * Since it is late here, further testing will have to wait until morning. I will post updates here, in this thread. * Thanks again for this. * Thread Starter [shoopiable](https://wordpress.org/support/users/shoopiable/) * (@shoopiable) * [11 years, 10 months ago](https://wordpress.org/support/topic/multisite-error-warning-cannot-modify-header-information/#post-5073877) * ok no problem, do let me know if I can be of any help if you need * [jon](https://wordpress.org/support/users/adiant/) * (@adiant) * [11 years, 10 months ago](https://wordpress.org/support/topic/multisite-error-warning-cannot-modify-header-information/#post-5073955) * I have sent you a possible fix by e-mail, for your testing. If it works, I will immediately release it as new version of the plugin. * Thanks. * Thread Starter [shoopiable](https://wordpress.org/support/users/shoopiable/) * (@shoopiable) * [11 years, 10 months ago](https://wordpress.org/support/topic/multisite-error-warning-cannot-modify-header-information/#post-5074000) * well done. that fixed it! * [jon](https://wordpress.org/support/users/adiant/) * (@adiant) * [11 years, 10 months ago](https://wordpress.org/support/topic/multisite-error-warning-cannot-modify-header-information/#post-5074002) * Version 2.11.1 has just been released, incorporating that change. * Thanks again for all your help with this. Viewing 7 replies - 1 through 7 (of 7 total) The topic ‘multisite error (Warning: Cannot modify header information)’ is closed to new replies. * ![](https://ps.w.org/jonradio-private-site/assets/icon-256x256.png?rev=3370795) * [My Private Site](https://wordpress.org/plugins/jonradio-private-site/) * [Frequently Asked Questions](https://wordpress.org/plugins/jonradio-private-site/#faq) * [Support Threads](https://wordpress.org/support/plugin/jonradio-private-site/) * [Active Topics](https://wordpress.org/support/plugin/jonradio-private-site/active/) * [Unresolved Topics](https://wordpress.org/support/plugin/jonradio-private-site/unresolved/) * [Reviews](https://wordpress.org/support/plugin/jonradio-private-site/reviews/) ## Tags * [header error](https://wordpress.org/support/topic-tag/header-error/) * [multisite](https://wordpress.org/support/topic-tag/multisite/) * 7 replies * 2 participants * Last reply from: [jon](https://wordpress.org/support/users/adiant/) * Last activity: [11 years, 10 months ago](https://wordpress.org/support/topic/multisite-error-warning-cannot-modify-header-information/#post-5074002) * Status: resolved