HELP! Getting PHP Warning: Cannot modify header information - headers already sent by plugins/cornerstone

[ssiwebdev]

Hi. I need help. I was editing a slide in LayerSlider when all of sudden, the admin side of the site stopped working. I can’t update anything. The content in layer disappeared. Buttons and tabs are not clickable. (If you click on one, nothing happens). I checked the error log and found this:

[09-Jun-2021 21:35:26 UTC] PHP Warning: Cannot modify header information - headers already sent by (output started at /home/ssicards/public_html/wp-content/plugins/cornerstone/includes/classes/common/class-locator.php:1) in /home/ssicards/public_html/wp-includes/rest-api/class-wp-rest-server.php on line 1642
[09-Jun-2021 21:35:26 UTC] PHP Warning: Cannot modify header information - headers already sent by (output started at /home/ssicards/public_html/wp-content/plugins/cornerstone/includes/classes/common/class-locator.php:1) in /home/ssicards/public_html/wp-includes/rest-api.php on line 675
[09-Jun-2021 21:35:26 UTC] PHP Warning: Cannot modify header information - headers already sent by (output started at /home/ssicards/public_html/wp-content/plugins/cornerstone/includes/classes/common/class-locator.php:1) in /home/ssicards/public_html/wp-includes/rest-api.php on line 676
[09-Jun-2021 21:35:26 UTC] PHP Warning: Cannot modify header information - headers already sent by (output started at /home/ssicards/public_html/wp-content/plugins/cornerstone/includes/classes/common/class-locator.php:1) in /home/ssicards/public_html/wp-includes/rest-api.php on line 677
[09-Jun-2021 21:35:26 UTC] PHP Warning: Cannot modify header information - headers already sent by (output started at /home/ssicards/public_html/wp-content/plugins/cornerstone/includes/classes/common/class-locator.php:1) in /home/ssicards/public_html/wp-includes/rest-api.php on line 678

I haven’t changed anything. I checked the functions,php and there is no space before <?php. I have no idea of what to do.

Thanks in advance!

[ruenel]

Hello @ssiwebdev,

Thanks for writing in! You will need to disable the debug mode to get rid of the PHP Warnings. You can do this by opening wp-config.php file and adding

define('WP_DEBUG', false);

/* That's all, stop editing! Happy blogging. */

When you revisit the page, you should no longer be seeing the PHP Warnings and you will be able to edit a slide.

Kindly let us know how it goes.

[ssiwebdev]

Hi, I looked at the wp-config.php and debug mode is already disabled. This is how it’s configured:

[ssiwebdev]

Also related to this issue is that all the options such as “Additional CSS” are gone from the “Customize” area from X-Theme

. The only thing available is “Widgets”. Basically, one second they were there and then suddenly they disappeared. I have no idea what to do.

[marc_a]

Hi @ssiwebdev,

To further investigate about your issue. Would you mind sharing your admin credential and FTP access to check the back-end settings? To do that, please give us the following information in a Secure Note.

• WordPress Login URL
• Admin level username and password
• FTP Access

You can find the Secure Note button at the bottom of your posts.

Thank you.

[ssiwebdev]

I just sent you a secure note with site, login name and password.
Thanks!

[marc_a]

Hi @ssiwebdev,

I just check your website and you have some site health issues. I advise that you fix the issue found on your site health page ( see secure note for the site health link).

Hope that helps and let us know how it goes.

Thank you.