Title: Cannot modify header information
Last modified: August 18, 2019

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# Cannot modify header information

 *  [Ambyomoron](https://wordpress.org/support/users/josiah-s-carberry/)
 * (@josiah-s-carberry)
 * [6 years, 9 months ago](https://wordpress.org/support/topic/cannot-modify-header-information-150/)
 * Could someone please explain the significance of this PHP message:
    `PHP Warning:
   Cannot modify header information - headers already sent by (output started at/
   blahblah/wp-content/plugins/yoast-seo-search-index-purge/src/Yoast_Purge_Attachment_Page_Server.
   php:46) in /blahblah/wp-content/plugins/wp-content-security-policy/includes/WP_CSP.
   php on line 548` This message is displayed regularly in the web server error 
   log. It occurs principally when a search engine spider visits my site. Is there
   something I should do to avoid this warning?

The topic ‘Cannot modify header information’ is closed to new replies.

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## Tags

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

 * 0 replies
 * 1 participant
 * Last reply from: [Ambyomoron](https://wordpress.org/support/users/josiah-s-carberry/)
 * Last activity: [6 years, 9 months ago](https://wordpress.org/support/topic/cannot-modify-header-information-150/)
 * Status: not resolved