I recently started seeing a PHP-related error that kept popping up while clicking around in my WordPress dashboard. Whenever I’d toggle a plugin, change themes, try to preview a post, it would pop up. How very annoying.
The text of the error was:
Warning: Cannot modify header information - headers already sent by (output started at /home/financia/public_html/wordpress/wp-config.php:97) in /home/financia/public_html/wordpress/wp-includes/pluggable.php on line 875
So, naturally, I went and looked line 875 in
pluggable.php but didn’t see any problems. Hmmm. Time to try other (possible) solutions.
I tried deactivating plugins. No effect. I switched themes. Nothing. I re-installed WordPress. The problem persisted.
I then contacted my host and they tried a number of things, including rolling PHP back to an earlier version. Nothing helped.
Then I popped into
wp-config.php and saw an extraneous line of code from a caching plugin that I was no longer using.
define('WPCACHEHOME', '/home/mysite/public_html/wordpress/wp-content/plugins/wp-super-cache/' ); //Added by WP-Cache Manager
Surely that’s the problem. Right? Wrong. Deleting it didn’t resolve the error.
I then scrolled to the bottom of that file and saw two extra lines of whitespace after the closing
?> tag. Bingo. Deleting those fixed the problem.