PLEASE HELP: Multiple "Cannot modify header information" after updating WordPress

[Passmore16]

Hi!

I work for a marketing agency in content, so don’t have much knowledge of technical wordpress/PHP stuff. I’ve recently updated the site’s theme and WordPress, and received multiple “Cannot modify header information” warnings, and now can’t log in to WordPress at all. Here are the warnings messages:

Warning : Cannot modify header information - headers already sent by (output started at /home/PAGE/public_html/wp-includes/functions.php:6114) in /home/PAGE/public_html/wp-login.php on line 515

Warning : Cannot modify header information - headers already sent by (output started at /home/PAGE/public_html/wp-includes/functions.php:6114) in /home/PAGE/public_html/wp-login.php on line 531

Warning : Cannot modify header information - headers already sent by (output started at /home/PAGE/public_html/wp-includes/functions.php:6114) in /home/PAGE/public_html/wp-includes/functions.php on line 7137

Warning : Cannot modify header information - headers already sent by (output started at /home/PAGE/public_html/wp-includes/functions.php:6114) in /home/PAGE/public_html/wp-includes/pluggable.php on line 1093

Warning : Cannot modify header information - headers already sent by (output started at /home/PAGE/public_html/wp-includes/functions.php:6114) in /home/PAGE/public_html/wp-includes/pluggable.php on line 1094

Warning : Cannot modify header information - headers already sent by (output started at /home/PAGE/public_html/wp-includes/functions.php:6114) in /home/PAGE/public_html/wp-includes/pluggable.php on line 1095

I have access to the PHP files through CPanel but have no idea what I’m looking for or what to change. Also, since receiving the error messages including “wp-login” I now can’t log into WordPress at all, and I am terrified I’ve broken our clients’ site. PLEASE HELP!!!

Thank you!

[phdr]

At approximately line 6114 of functions.php is a trigger_error() statement. This is what is (likely) producing the output. What does the ‘view source’ in the browser show for a page that is producing what you have posted?

There are two things to deal with - 1) find what error is being output by the trigger_error() statement and likely fix it, or if it is not a serious problem, it means that 2) php’s display_errors setting has been turned on, and it needs to be turned off.

[Passmore16]

Thank you for your help!