I'm using my ISP's cPanel X File Manager to change / modify my Xoops PHP files, and I keep breaking my site. What's wrong?

cPanel X's File Manager module seems to add trailing carriage returns at the end of the PHP file (after the !>). You need to edit your PHP files some other way and upload them, or re-edit the file remove the extra lines.

Added by Carnuke: I also found this to be the case when editing my mainfile.php with cpanel. It left trailing lines after the !> and caused all kinds of problems.

Mithrandir's comment: Trailing carriage returns after the ?> will start the HTML output and cause errors if the code is subsequently trying to add/modify the header information - such as a header('location:') redirection or other header information

These carriage returns in mainfile.php can essentially result in the dreaded blank pages.

This Q&A was found on XOOPS Web Application System : https://xoops.org/modules/smartfaq/faq.php?faqid=375