Warning: Cannot modify header information

Okay, so I know there’s a ton of content and solutions out there, which I have spent a fair amount of time investigating. However, I have yet to find a solution.

Though the following error is revealed, the action I was looking to take place executes fine and there is nothing ‘visually’ wrong with the site.

Suggestions?

Warning: Cannot modify header information - headers already sent by (output started at /home/xxxxxx/public_html/xxxxxx/wp-content/themes/fiono/functions.php:366) in /home/xxxxxx/public_html/xxxxxx/wp-includes/pluggable.php on line 897

Line 897: header("Location: $location", true, $status);

I have checked and rechecked numerous php files and they do not seem to have any white space problems. If this is truly a header issue, I’m miffed, as this error just occurred without any modifications to the files identified, or any of the theme files.

I also receive a similar error for line 99 of theme-editor.php

Thanks, Scott