Title: Cannot modify header information – headers already
Last modified: May 19, 2019

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# Cannot modify header information – headers already

 *  Resolved [Ambyomoron](https://wordpress.org/support/users/josiah-s-carberry/)
 * (@josiah-s-carberry)
 * [6 years, 12 months ago](https://wordpress.org/support/topic/cannot-modify-header-information-headers-already-2/)
 * With the upgrade to Yoast 11.2.1 the following warning started to appear:
 * `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`
 * Before that upgrade, I never saw the warning, so something changed in Yoast (
   and not in Content Security Policy plugin) that is causing it.
 * I humbly ask that the authors of Yoast take a look and fix any errors that might
   have been introduced by ver 11.2.1. Note that [https://stackoverflow.com/questions/8028957/how-to-fix-headers-already-sent-error-in-php](https://stackoverflow.com/questions/8028957/how-to-fix-headers-already-sent-error-in-php)
   has an extensive discussion of the issue, if that is of any help.

Viewing 1 replies (of 1 total)

 *  [Pcosta88](https://wordpress.org/support/users/pcosta88/)
 * (@pcosta88)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/cannot-modify-header-information-headers-already-2/#post-11580485)
 * Hi!
 * That sounds like a plugin or theme conflict. Can you try and gather as much information
   for us as possible? Please perform the following:
 * 1. Make sure you are using the most recent WordPress Core, v5.2.1. If you are
   not sure what version you have or how to update, your host provider can help.
   Also, be sure to update your Yoast to v11.3 and update your non-Yoast plugins.
 * 2. Make sure the issue doesn’t persist when Yoast SEO is disabled.
 * 3. If the issue only happens when Yoast is enabled, please [Check for conflicts](https://kb.yoast.com/kb/how-to-check-for-plugin-conflicts).
 * 4. Check for [JavaScript errors with your console](https://kb.yoast.com/kb/how-to-find-javascript-errors-with-your-browsers-console).
 * If you find any JavaScript errors related to Yoast SEO or if there is a conflict
   with a plugin or a theme, you can create a [new GitHub issue](https://github.com/Yoast/wordpress-seo/issues/new)
   for our developers. Please report the issue to a third party developer as well.
 * If you didn’t find any conflicts or errors, we think the issue is specific to
   your site. We’d need to investigate further but are unable to do so on these 
   forums. You can [purchase Yoast SEO Premium](https://yoast.com/wordpress/plugins/seo/)
   and receive our Premium email support and we can help you further.

Viewing 1 replies (of 1 total)

The topic ‘Cannot modify header information – headers already’ is closed to new 
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## Tags

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

 * 1 reply
 * 2 participants
 * Last reply from: [Pcosta88](https://wordpress.org/support/users/pcosta88/)
 * Last activity: [6 years, 11 months ago](https://wordpress.org/support/topic/cannot-modify-header-information-headers-already-2/#post-11580485)
 * Status: resolved