Title: Warning: cannot modify header error
Last modified: August 30, 2016

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# Warning: cannot modify header error

 *  Resolved [barkington](https://wordpress.org/support/users/barkington/)
 * (@barkington)
 * [10 years, 8 months ago](https://wordpress.org/support/topic/warning-cannot-modify-header-error/)
 * I am getting the error; Warning: Cannot modify header information – headers already
   sent by (output started at /home/jtsme0/public_html/barkington.net/wp-includes/
   functions.php:1) in /home/jtsme0/public_html/barkington.net/wp-includes/pluggable.
   php on line 1207
 * I have deactivated all plugins and it still happens so its not those. I also 
   have checked for any spaces in the first line of the code on functions.php and
   no space.
 * Please help.
    Regards Felicia

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

 *  Moderator [James Huff](https://wordpress.org/support/users/macmanx/)
 * (@macmanx)
 * [10 years, 8 months ago](https://wordpress.org/support/topic/warning-cannot-modify-header-error/#post-6612210)
 * You have unexpected whitespace (either a space or an entire line) on line 1 of
   the `/wp-includes/functions.php` file. See [this guide](https://codex.wordpress.org/FAQ_Troubleshooting#How_do_I_solve_the_Headers_already_sent_warning_problem.3F)
   for more info.
 * Alternatively, replacing the file with one from a fresh download may resolve 
   the issue.
 *  Thread Starter [barkington](https://wordpress.org/support/users/barkington/)
 * (@barkington)
 * [10 years, 8 months ago](https://wordpress.org/support/topic/warning-cannot-modify-header-error/#post-6612254)
 * Thanks, just ended up replacing the entire functions.php file.
 * No idea how that happened -__-
 *  Moderator [James Huff](https://wordpress.org/support/users/macmanx/)
 * (@macmanx)
 * [10 years, 8 months ago](https://wordpress.org/support/topic/warning-cannot-modify-header-error/#post-6612267)
 * You’re welcome!

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

The topic ‘Warning: cannot modify header error’ is closed to new replies.

## Tags

 * [headers already sent](https://wordpress.org/support/topic-tag/headers-already-sent/)
 * [warning](https://wordpress.org/support/topic-tag/warning/)

 * In: [Fixing WordPress](https://wordpress.org/support/forum/how-to-and-troubleshooting/)
 * 3 replies
 * 2 participants
 * Last reply from: [James Huff](https://wordpress.org/support/users/macmanx/)
 * Last activity: [10 years, 8 months ago](https://wordpress.org/support/topic/warning-cannot-modify-header-error/#post-6612267)
 * Status: resolved

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