Title: Cannot modify header information – Firefox
Last modified: August 18, 2016

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# Cannot modify header information – Firefox

 *  [gstewart](https://wordpress.org/support/users/gstewart/)
 * (@gstewart)
 * [19 years, 3 months ago](https://wordpress.org/support/topic/cannot-modify-header-information-firefox/)
 * I have WP 2.1.1 and when using Firefox 2.0 to update the sidebar widgets page
   I get:
    Warning: Cannot modify header information – headers already sent by (
   output started at /home/4246/domains/bigdadoo.com/html/blog/wp-admin/admin-header.
   php:16) in /home/4246/domains/bigdadoo.com/html/blog/wp-includes/functions.php
   on line 1218
 * This only occurs on Firefox 2.0 and works properly when using IE6. The blog also
   does not display the post title on FF2.0, and again on IE6, it’s good. [http://www.bigdaddo.com/blog](http://www.bigdaddo.com/blog)
 * I’ve checked both files and there is no white space after the ?> or after the
   <?PHP

Viewing 1 replies (of 1 total)

 *  [sthrudel](https://wordpress.org/support/users/sthrudel/)
 * (@sthrudel)
 * [19 years, 3 months ago](https://wordpress.org/support/topic/cannot-modify-header-information-firefox/#post-529123)
 * Try setting permissions of subdirectories in /path/blog/wp-content/uploads/ to
   0777.

Viewing 1 replies (of 1 total)

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

## Tags

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

 * In: [Fixing WordPress](https://wordpress.org/support/forum/how-to-and-troubleshooting/)
 * 1 reply
 * 2 participants
 * Last reply from: [sthrudel](https://wordpress.org/support/users/sthrudel/)
 * Last activity: [19 years, 3 months ago](https://wordpress.org/support/topic/cannot-modify-header-information-firefox/#post-529123)
 * Status: not resolved

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