This is a common PHP error that usually happens when you attempt to send a HTTP header after some output has already been sent to the browser.

In this case, the output has been started at file jscript_framework.php on line 17, which is preventing the header modification in class.abuseipdb_observer.php on line 137.

The issue lies in the sequence of operations where some content was output before the headers could be completely set. This could be due to:

Printing some text or HTML before calling a header function.
A PHP or HTML file which has whitespace or an empty line before the opening PHP tag (<?php) or after the closing PHP tag (?>), if used.
A UTF-8 Byte Order Mark (BOM) at the beginning of one of the files.
Using echo, print, printf, or die functions before setting headers.
To fix this issue, check the file /home/brucebli/public_html/koolbadges.co.uk/includes/templates/responsive_avonlee_contempo/jscript/jscript_framework.php specifically at line 17 and make sure there's no output before the headers are set in the file class.abuseipdb_observer.php.

If this doesn't solve your problem, consider using output buffering by placing ob_start(); at the beginning of your PHP script. This function will turn output buffering on. While output buffering is active no output is sent from the script (other than headers), instead the output is stored in an internal buffer. You can then use ob_end_flush(); or ob_end_clean(); at the end of the script to send output and turn off output buffering. However, it's better to solve the actual problem of why output is being sent too early, if possible.