Title: warning: cannot modify header information
Last modified: December 4, 2017

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# warning: cannot modify header information

 *  [camanicnack](https://wordpress.org/support/users/camanicnack/)
 * (@camanicnack)
 * [8 years, 5 months ago](https://wordpress.org/support/topic/warning-cannot-modify-header-information-186/)
 * I am receiving an error message of “WARNING: CANNOT MODIFY HEADER INFORMATION–
   HEADERS ALREADY SENT BY (OUTPUT STARTED AT” through out my wordpress website 
   each time I use the php code within my page templates of header(‘location:’),
   example header(‘Location: [http://demo.camavision.com/VCSWeb/‘](http://demo.camavision.com/VCSWeb/‘)).
   This code was working fine awhile ago, about a week ago to be exact. I tried 
   shutting off all the plugins, updating the wordpress main source code, even tried
   going into the source code and fixing it but it just seems that a different line
   with same message of modify headers pops up… And another one… And another one…
   and etc. Getting WARNING: CANNOT MODIFY HEADER INFORMATION on multiple lines 
   of the base code. As an example: “WARNING: CANNOT MODIFY HEADER INFORMATION –
   HEADERS ALREADY SENT BY (OUTPUT STARTED AT C:\WAMP64\WWW\VCSWEB\WP-INCLUDES\FORMATTING.
   PHP:5084)” Basically too many to fix for the source code, and all I do is just
   add a php code of header(‘Location: [http://demo.camavision.com/VCSWeb/‘](http://demo.camavision.com/VCSWeb/‘))
   in the template. It all comes down that the main source code from wordpress seems
   to either have a bunch of spaces or something wrong with the php <?php & ?> coding.
   Please fix….

Viewing 4 replies - 1 through 4 (of 4 total)

 *  Theme Author [marsian](https://wordpress.org/support/users/marsian/)
 * (@marsian)
 * [8 years, 5 months ago](https://wordpress.org/support/topic/warning-cannot-modify-header-information-186/#post-9759343)
 * Did you modify any theme file?
    Did you try running the site all plugins deactivate?
 * there might be some empty lines before of after <?php ?>
 *  Thread Starter [camanicnack](https://wordpress.org/support/users/camanicnack/)
 * (@camanicnack)
 * [8 years, 5 months ago](https://wordpress.org/support/topic/warning-cannot-modify-header-information-186/#post-9760153)
 * I did not modify any of the theme files, and when I deactivated all the plugins,
   it is still having the same issue.
 *  Thread Starter [camanicnack](https://wordpress.org/support/users/camanicnack/)
 * (@camanicnack)
 * [8 years, 5 months ago](https://wordpress.org/support/topic/warning-cannot-modify-header-information-186/#post-9760159)
 * We even noticed it happen when we updated the the theme from the last update.
   So after the update, the error started popping up.
 *  Theme Author [marsian](https://wordpress.org/support/users/marsian/)
 * (@marsian)
 * [8 years, 5 months ago](https://wordpress.org/support/topic/warning-cannot-modify-header-information-186/#post-9760754)
 * It will be difficult to diagnose the problem without looking at the files. theme
   is working fine on our local and remote servers.
 * Change the theme to confirm the issue is with the theme. let me know. if possible
   mail me a temporary admin access details.

Viewing 4 replies - 1 through 4 (of 4 total)

The topic ‘warning: cannot modify header information’ is closed to new replies.

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## Tags

 * [Cannot modify header information](https://wordpress.org/support/topic-tag/cannot-modify-header-information/)

 * 4 replies
 * 2 participants
 * Last reply from: [marsian](https://wordpress.org/support/users/marsian/)
 * Last activity: [8 years, 5 months ago](https://wordpress.org/support/topic/warning-cannot-modify-header-information-186/#post-9760754)
 * Status: not resolved