Paypal Module Express Checkout Error in General Discussions Posted September 20, 2020 1 hour ago, SolidAmerica said: Warning: Cannot modify header information - headers already sent by (output started at /home/www/mysellingstoreexample.com/.com/stores/includes/system/versioned/220.127.116.11/customer.php:62) in /home/www/mysellingstoreexample.com/.com/stores/includes/functions/general.php on line 36 This says that you have display_errors turned on. You can add ini_set('display_errors', '0'); to includes/configure.php to turn it off. Or turn it off in your hosting account if they allow you to do that. You should not have display_errors turned on in your live store. The warning and notices will be fixed in the 18.104.22.168 release.