Title: Installing first wordpress theme – Cannot modify header information
Last modified: August 20, 2016

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# Installing first wordpress theme – Cannot modify header information

 *  [Jones Elizabeth](https://wordpress.org/support/users/leonagrey/)
 * (@leonagrey)
 * [13 years, 10 months ago](https://wordpress.org/support/topic/installing-first-wordpress-theme-cannot-modify-header-information/)
 * Hi All,
 * I have just started to learn about wordpress development. I have created a theme(
   using a teaching book as guidance), & now I’m trying to use my theme.
 *  I keep getting the following message:
    Fatal error: Call to undefined function
   have_loops() in /home/greentes/public_html/wp/wp-content/themes/greenone/index.
   php on line 9
 * How do I solve this please? 🙂
 * I also keep getting this error:
 * Warning: Cannot modify header information – headers already sent by (output started
   at /home/greentes/public_html/wp/wp-content/themes/greenone/functions.php:5) 
   in /home/greentes/public_html/wp/wp-includes/option.php on line 563
 * Any ideas please? I’m a bit clueless at present.
 * Thank you 🙂

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

 *  Thread Starter [Jones Elizabeth](https://wordpress.org/support/users/leonagrey/)
 * (@leonagrey)
 * [13 years, 10 months ago](https://wordpress.org/support/topic/installing-first-wordpress-theme-cannot-modify-header-information/#post-2970140)
 * I have added <? ob_start(); ?> and <? ob_flush(); ?> to the index.php to try 
   and solve this. It hasn’t worked.
 *  It is at [http://greentest1.co.uk/wp/](http://greentest1.co.uk/wp/) (I am using
   the domain to learn wordpress development)
 *  [Amy Hendrix (sabreuse)](https://wordpress.org/support/users/sabreuse/)
 * (@sabreuse)
 * [13 years, 10 months ago](https://wordpress.org/support/topic/installing-first-wordpress-theme-cannot-modify-header-information/#post-2970150)
 * What’s around line 5 of your functions.php?
 *  Thread Starter [Jones Elizabeth](https://wordpress.org/support/users/leonagrey/)
 * (@leonagrey)
 * [13 years, 10 months ago](https://wordpress.org/support/topic/installing-first-wordpress-theme-cannot-modify-header-information/#post-2970194)
 * Thanks, for taking an interest . This is all from line 5 (very long):
 * register_sidebar ( array( ‘id’ => ‘primary’, ‘name’ => _( ‘primary’ ), ‘description’
   => _(‘This is the primary sidebar.’), ‘before_widget’ => ‘<div id=”%1$s” class
   =”widget%2$s”>’, ‘after_widget’ => ‘</div>’, ‘before_title’ => ‘<h3 class=”widget-
   title”> ‘, ‘after_title’ => ‘</h3>’ ) ); } ?>
 *  Thread Starter [Jones Elizabeth](https://wordpress.org/support/users/leonagrey/)
 * (@leonagrey)
 * [13 years, 10 months ago](https://wordpress.org/support/topic/installing-first-wordpress-theme-cannot-modify-header-information/#post-2970349)
 * Has anyone got any ideas please?

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

The topic ‘Installing first wordpress theme – Cannot modify header information’ 
is closed to new replies.

 * 4 replies
 * 2 participants
 * Last reply from: [Jones Elizabeth](https://wordpress.org/support/users/leonagrey/)
 * Last activity: [13 years, 10 months ago](https://wordpress.org/support/topic/installing-first-wordpress-theme-cannot-modify-header-information/#post-2970349)
 * Status: not resolved

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