Title: CSS link creating header errors… Last modified: December 25, 2019 --- # CSS link creating header errors… * [jwrbloom](https://wordpress.org/support/users/jwrbloom/) * (@jwrbloom) * [6 years, 3 months ago](https://wordpress.org/support/topic/css-link-creating-header-errors/) * I’ve written a little plugin for myself, just putting my custom functions in there for my site. Everything is going well except trying to link CSS files to it. * One of my functions was a standalone file before I decided to create a function for it instead of using INCLUDE. It works as its intended to work, except for the CSS. * ``` ``` * I started it above the Warning: Cannot modify header information – headers already sent by (output > started at /public_html/wp-content/plugins/csi_custom.php:2) in /home2/csi/ > public_html/wp-includes/functions.php on line 6029 > Warning: Cannot modify header information – headers already sent by (output > started at /public_html/wp-content/plugins/csi_custom.php:2) in /home2/csi/ > public_html/wp-admin/includes/misc.php on line 1252 > Warning: Cannot modify header information – headers already sent by (output > started at /public_html/wp-content/plugins/csi_custom.php:2) in /home2/csi/ > public_html/wp-admin/admin-header.php on line 9 - This topic was modified 6 years, 3 months ago by [Jan Dembowski](https://wordpress.org/support/users/jdembowski/). Reason: Moved to Fixing WordPress, this is not a Developing with WordPress topic Viewing 2 replies - 1 through 2 (of 2 total) * Moderator [bcworkz](https://wordpress.org/support/users/bcworkz/) * (@bcworkz) * [6 years, 3 months ago](https://wordpress.org/support/topic/css-link-creating-header-errors/#post-12267889) * Plugin files are processed very early. Anything outside of `` tags generates output. When WP then later tries to send its headers, your early output causes errors. If you want to directly output link tags, they need to be within the ` ` section for the HTML to validate. To do so, you need to either edit the theme template containing the head section, or hook an action that fires at the right time. You could use the “wp_print_scripts” action for this, though your link may not exactly land in the optimal place. It’ll still work as long as there are no subsequent overrides in other CSS. * The proper way to reference external stylesheets is through `wp_enqueue_style()`. Then you can be assured the resulting link tag occurs in the optimal location. * You’ll also want to avoid relative file references, they work inconsistently in WP. Always use the full absolute URL. You can get your plugin’s base URL with` plugin_dir_url()` which will work for any WP installation. You would never hardcode a full URL, always get it from a function. * Thread Starter [jwrbloom](https://wordpress.org/support/users/jwrbloom/) * (@jwrbloom) * [6 years, 3 months ago](https://wordpress.org/support/topic/css-link-creating-header-errors/#post-12268305) * I typically start PHP includes with ABSPATH. * For this, I went ahead and put the CSS link in the theme’s designated “custom HTML” section. Viewing 2 replies - 1 through 2 (of 2 total) The topic ‘CSS link creating header errors…’ is closed to new replies. * In: [Fixing WordPress](https://wordpress.org/support/forum/how-to-and-troubleshooting/) * 2 replies * 2 participants * Last reply from: [jwrbloom](https://wordpress.org/support/users/jwrbloom/) * Last activity: [6 years, 3 months ago](https://wordpress.org/support/topic/css-link-creating-header-errors/#post-12268305) * Status: not resolved ## Topics ### Topics with no replies ### Non-support topics ### Resolved topics ### Unresolved topics ### All topics