Title: Another cannot modify header information error
Last modified: August 20, 2016

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# Another cannot modify header information error

 *  Resolved [cw6365](https://wordpress.org/support/users/cw6365/)
 * (@cw6365)
 * [14 years, 5 months ago](https://wordpress.org/support/topic/another-cannot-modify-header-information-error/)
 * Another post on this subject, i’ve looked for white space in the main files but
   all seems to be ok. I have one error when adding a shortcode in the functions
   file, but i’ve never had the error in the header before and we’re months into
   coding the site.
 * Cannot modify header information – headers already sent by (output started at/
   var/www/vhosts/clienttestdomain.co.uk/httpdocs/wp-content/themes/kino/header.
   php:16) in /var/www/vhosts/clienttestdomain.co.uk/httpdocs/wp-includes/pluggable.
   php on line 754
 * it was when i added a function `if(wp_update_user(array('ID' => $currentUser-
   >ID, 'user_pass' => $newpassword)))`
 * in this function, if i swap this out for a return statement eg $output .= “hello
   world”; it is fine?
 * _[Code moderated as per the [Forum Rules](http://codex.wordpress.org/Forum_Welcome#Posting_Code).
   Please use the [pastebin](http://wordpress.pastebin.com/)]_
 * The second error is in an admin plugin, this didn’t happen on my local server
 * `Warning: Cannot modify header information - headers already sent by (output 
   started at /var/www/vhosts/clienttestdomain.co.uk/httpdocs/wp-content/plugins/
   film_db/filmdb.php:81) in /var/www/vhosts/clienttestdomain.co.uk/httpdocs/wp-
   includes/pluggable.php on line 934`
 * I’ve checked the code and it still all works fine just shows this error, here
   is the method of the object that contains the code with line 81
 * _[Code moderated as per the [Forum Rules](http://codex.wordpress.org/Forum_Welcome#Posting_Code).
   Please use the [pastebin](http://wordpress.pastebin.com/)]_
 * I don’t know where to start, what does this error even mean, what headers sent?
   Any help would be gladely received, i’m a broken man!!!

Viewing 8 replies - 1 through 8 (of 8 total)

 *  Thread Starter [cw6365](https://wordpress.org/support/users/cw6365/)
 * (@cw6365)
 * [14 years, 5 months ago](https://wordpress.org/support/topic/another-cannot-modify-header-information-error/#post-2434183)
 * ahh i’ve sorted the second one, it is the redirect, i forgot about adding it.
   Just the first one please
 *  [esmi](https://wordpress.org/support/users/esmi/)
 * (@esmi)
 * [14 years, 5 months ago](https://wordpress.org/support/topic/another-cannot-modify-header-information-error/#post-2434185)
 * See [Solving “headers already sent” warnings](http://codex.wordpress.org/FAQ_Troubleshooting#How_do_I_solve_the_Headers_already_sent_warning_problem.3F).
 *  Thread Starter [cw6365](https://wordpress.org/support/users/cw6365/)
 * (@cw6365)
 * [14 years, 5 months ago](https://wordpress.org/support/topic/another-cannot-modify-header-information-error/#post-2434199)
 * first port of call my friend along with 20+ posts on the forum but it never seems
   to work
 *  Thread Starter [cw6365](https://wordpress.org/support/users/cw6365/)
 * (@cw6365)
 * [14 years, 5 months ago](https://wordpress.org/support/topic/another-cannot-modify-header-information-error/#post-2434203)
 * Yaayyy, i’ve got the solution, havent got a clue what it does or its side effects
   but it has solved both the problems, add the following to functions.php
 *     ```
       add_action('init', 'do_output_buffer');
   
       	function do_output_buffer() {
               ob_start();
       	}
       ```
   
 * found over at [stack overflow](http://stackoverflow.com/questions/7381661/cannot-modify-header-information-headers-already-sent-by-wordpress-issue)
 *  [esmi](https://wordpress.org/support/users/esmi/)
 * (@esmi)
 * [14 years, 5 months ago](https://wordpress.org/support/topic/another-cannot-modify-header-information-error/#post-2434204)
 * Does nobody ever read error messages these days?
 * > (output started at /var/www/vhosts/clienttestdomain.co.uk/httpdocs/wp-content/
   > plugins/film_db/filmdb.php:81)
 * Now guess which plugin needs to be deactiveated/deleted?
 *  Thread Starter [cw6365](https://wordpress.org/support/users/cw6365/)
 * (@cw6365)
 * [14 years, 5 months ago](https://wordpress.org/support/topic/another-cannot-modify-header-information-error/#post-2434321)
 * it’s a custom plugin that runs half the system, what good is deleting/deactivating
   going to do? dont comment if your no use
 *  [esmi](https://wordpress.org/support/users/esmi/)
 * (@esmi)
 * [14 years, 5 months ago](https://wordpress.org/support/topic/another-cannot-modify-header-information-error/#post-2434332)
 * Your custom plugin is the one generating the errors. You asked for the cause.
   That’s it.
 *  Thread Starter [cw6365](https://wordpress.org/support/users/cw6365/)
 * (@cw6365)
 * [14 years, 5 months ago](https://wordpress.org/support/topic/another-cannot-modify-header-information-error/#post-2434361)
 * what by deleting the plugin, very helpful!

Viewing 8 replies - 1 through 8 (of 8 total)

The topic ‘Another cannot modify header information error’ is closed to new replies.

## Tags

 * [cannot](https://wordpress.org/support/topic-tag/cannot/)
 * [headers](https://wordpress.org/support/topic-tag/headers/)
 * [Modify](https://wordpress.org/support/topic-tag/modify/)

 * In: [Fixing WordPress](https://wordpress.org/support/forum/how-to-and-troubleshooting/)
 * 8 replies
 * 2 participants
 * Last reply from: [cw6365](https://wordpress.org/support/users/cw6365/)
 * Last activity: [14 years, 5 months ago](https://wordpress.org/support/topic/another-cannot-modify-header-information-error/#post-2434361)
 * Status: resolved

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