Title: Error: "Warning: Cannot modify header information"
Last modified: August 30, 2016

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# Error: "Warning: Cannot modify header information"

 *  Resolved [dannybevz](https://wordpress.org/support/users/dannybevz/)
 * (@dannybevz)
 * [10 years, 5 months ago](https://wordpress.org/support/topic/error-warning-cannot-modify-header-information-5/)
 * Hi there,
 * Thanks for the great plugin. I emailed about an issue that’s flared up for me,
   but perhaps you don’t offer support there (understandable).
 * The issue happens since the last plugin update which for me was this past weekend.
 * Whenever I do some (I guess database) tasks in the WP backend like saving a draft,
   changing a user level, clearing spam comments and those sorts of things this 
   error displays:
 * Warning: Cannot modify header information – headers already sent by (output started
   at PATHHIDDEN/wp-content/plugins/jm-twitter-cards/classes/admin/preview.php:30)
   in PATHHIDDEN/wp-includes/pluggable.php on line 1207
 * However, despite the error/white screen showing the task you try to do has worked
   in the background.
 * I see on Twitter that the plugin’s functionality (the cards) is still working.
   It’s just this pesky error that shows. If I disable your plugin, the error does
   not happen, but then I lose the cards of course.
 * When saving a post draft the error is a bit different (2 lines) like this:
 * Warning: Cannot modify header information – headers already sent by (output started
   at PATHHIDDEN/wp-content/plugins/jm-twitter-cards/classes/admin/preview.php:30)
   in PATHHIDDEN/wp-admin/post.php on line 242
 * Warning: Cannot modify header information – headers already sent by (output started
   at PATHHIDDEN/wp-content/plugins/jm-twitter-cards/classes/admin/preview.php:30)
   in PATHHIDDEN/wp-includes/pluggable.php on line 1207
 * Is there something for me to change in my WP files? Does the plugin need an additional
   update by you?
 * I noticed someone had replied in the support thread before this one about an 
   issue that sounded the same so it might not be me alone.
 * Thanks in advance for any help.
 * [https://wordpress.org/plugins/jm-twitter-cards/](https://wordpress.org/plugins/jm-twitter-cards/)

Viewing 6 replies - 1 through 6 (of 6 total)

 *  Anonymous User 10765487
 * (@anonymized-10765487)
 * [10 years, 5 months ago](https://wordpress.org/support/topic/error-warning-cannot-modify-header-information-5/#post-6804197)
 * Hi,
 * 1 : do not show full path of your installation, it’s insecure
    2 : you should
   not show warnings in a live site, it’s insecure 3: warning should not be there
   so it’s a bug but it’s not a blocking error, anyway I should look into this when
   I get time.
 *  Thread Starter [dannybevz](https://wordpress.org/support/users/dannybevz/)
 * (@dannybevz)
 * [10 years, 5 months ago](https://wordpress.org/support/topic/error-warning-cannot-modify-header-information-5/#post-6804198)
 * I will disable the plugin for now then, unfortunately.
 * Thanks for looking into it.
 *  Anonymous User 10765487
 * (@anonymized-10765487)
 * [10 years, 5 months ago](https://wordpress.org/support/topic/error-warning-cannot-modify-header-information-5/#post-6804200)
 * understandable 🙂
 *  Thread Starter [dannybevz](https://wordpress.org/support/users/dannybevz/)
 * (@dannybevz)
 * [10 years, 5 months ago](https://wordpress.org/support/topic/error-warning-cannot-modify-header-information-5/#post-6804204)
 * Are the paths above now safe to show? Edited the original post here.
 *  Anonymous User 10765487
 * (@anonymized-10765487)
 * [10 years, 5 months ago](https://wordpress.org/support/topic/error-warning-cannot-modify-header-information-5/#post-6804208)
 * yep 🙂
 *  Anonymous User 10765487
 * (@anonymized-10765487)
 * [10 years, 2 months ago](https://wordpress.org/support/topic/error-warning-cannot-modify-header-information-5/#post-6804526)
 * Should be fixed in 7.4.0

Viewing 6 replies - 1 through 6 (of 6 total)

The topic ‘Error: "Warning: Cannot modify header information"’ is closed to new 
replies.

 * ![](https://s.w.org/plugins/geopattern-icon/jm-twitter-cards.svg)
 * [JM Twitter Cards](https://wordpress.org/plugins/jm-twitter-cards/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/jm-twitter-cards/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/jm-twitter-cards/)
 * [Active Topics](https://wordpress.org/support/plugin/jm-twitter-cards/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/jm-twitter-cards/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/jm-twitter-cards/reviews/)

## Tags

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

 * 6 replies
 * 2 participants
 * Last reply from: Anonymous User 10765487
 * Last activity: [10 years, 2 months ago](https://wordpress.org/support/topic/error-warning-cannot-modify-header-information-5/#post-6804526)
 * Status: resolved