Warning: Cannot modify header information - headers already sent by

Suddenly getting a "Warning: Cannot modify header information - headers already sent by.." error but cannot find any spaces in the code on my index.php page that would cause this. See the attachment. Anywhere else I should look?

The error says the line is index.php line 1... it could be a space at the end of that line, or maybe in the connections/rfl.php page that is referenced on line 1.

I double-checked both pages and found no spaces. I placed "<?php ob_start();?>" at the top of the index page and the warning no longer displays.

??

If you send me FTP access and a URL to reproduce then I could find the issue.

Just a thought... if the 'authenticate' code block was positioned just under the require_once code lines(i.e., before the other blocks), would that eliminate the need for any buffering so I could then remove the '<?php ob_start(); ?>' that I placed at the page top (which does solve the issue)?

It depends on where the blank lines of code or comments are. If it is above those, then it wouldn't have the error. I'd have to debug to see where the error occurs. It says line 1, so you probably can't get the code above that. If you send me a url to reproduce the issue and FTP access I can tell you exactly what is going on.

[16-Jan-2021 18:39:25 UTC] PHP Warning: Cannot modify header information - headers already sent by (output started at /home/thecenterforimma/public_html/WA_eCart/cficart_PHP.php:4) in /home/thecenterforimma/public_html/products_detail.php on line 43

There was some odd code on the top of the cart include that didn't belong. I deleted it and I think that should resolve this issue.

download /WA_eCart/cficart_PHP.php to get the updated file.

Files attached or you can pop in and look...

Warning: chdir(): No such file or directory (errno 2) in /home/thecenterforimma/public_html/webassist/framework/ajax_wrapper.php on line 30

Warning: require(/home/thecenterforimma/public_html/webassist/framework/confirm_cart.php): failed to open stream: No such file or directory in /home/thecenterforimma/public_html/webassist/framework/ajax_wrapper.php on line 40

Fatal error: require(): Failed opening required '/home/thecenterforimma/public_html/webassist/framework/confirm_cart.php' (include_path='.:/opt/cpanel/ea-php71/root/usr/share/pear') in /home/thecenterforimma/public_html/webassist/framework/ajax_wrapper.php on line 40

Is there a URL I can use to browse the site and see the error?