Troubleshooting Warning Messages
PHP Warning messages should not be displayed under normal usage. Seeing them indicates that a debugging option is switched on. We recommend keeping them off during normal use.
Navigate to Configuration > System Settings > General Settings (prior to WHMCS 8.0, Setup > General Settings).
Select the Other tab and scroll down to the bottom of the page.
UNtick the Display Errors option.
and click Save Changes.
The Display Errors option might also be enabled in the configuration.php file. So it's worth checking there too.
Open the configuration.php file in your WHMCS directory on your server.
Look for the following line of code and remove it if present:
$display_errors = true;
Save the file and upload to the server.
If the Display Error options are switched off and you're still seeing warning message, it indicates the Error Reporting level in your server's PHP Configuration is too high. This is a PHP configuration level issue and therefore for shared or reseller users, may require the assistance of your web hosting provider.
In WHM navigate to Service Configuration >> PHP Configuration Editor >> Advanced
Scroll down to the error_reporting setting:
Change the value to:
E_ALL & ~E_WARNING & ~E_USER_WARNING & ~E_NOTICE & ~E_USER_NOTICE & ~E_STRICT & ~E_DEPRECATED & ~E_USER_DEPRECATED