WP Error Fix: Cannot modify header - already sent - on line X« Back to Questions List

DO NOT CHANGE: functions.php

95% of these errors are because you changed the [functions.php] file generated by Export Kit - DO NOT CHANGE this file. You should not modify the functions file in any way. Create a custom.php file and edit that – DO NOT CHANGE THE FUNCTIONS FILE – or you WILL get output errors.

Your functions.php file is generated by Export Kit on each export = the file may change.  What you should do is enable Custom Templates with your output - you only need to do this once (or create custom.php and custom.css manually).

Plugin Conflicts

The other 5% of these errors are related to plugins. With WordPress there are many different plugin developers, and not all plugins work with all themes. There are rare cases where a plugin related to menus, may output the buffer incorrectly, causing an error in the theme.

Best solution is to do a fresh WP install, then test each plugin to find the issue - the quick solution is to increase the output_buffering on your server.


You should read about output_buffering online before you play with this - as it can slow your server down.

Read More: PHP Configurations

Added March 1, 2015 4:34 pm

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Last Answered 10 years ago by admin

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