php blank page

I'm trying to use the tag {php}, but I can not, even using just {php}{/php}

The pages that try to use are blank

By default, WHMCS locks the {php} tag from template usage, and this is the expected behavior.

I wouldn't get too used to using it, as it's highly frowned upon, however if you go to admin -> setup -> general settings -> security, you can enable this feature.

Again, don't get too used to using it, I wouldn't be terribly surprised if that got yanked out in v7.

using {php} in smarty has been frowned upon for quite some time, it was disabled by default in smarty3, and , again, I wouldn't be totally surprised if it was removed entirely in future versions of smarty.

you need to enable support of {php} tag from Admin Area -> Setup -> General Settings -> Security Tab -> *Allow Smarty PHP Tags*

but it is recommended to write your PHP logic in ActionHook function and pass the results to Smarty, this is better and safe

An option was added to WHMCS 6 to enable use of the potentially dangerous {php} tag in custom templates. This option is disabled by default but can be enabled if required in Setup > General Settings > Security. We strongly encourage using hook functions over php code blocks inside of templates for backend interaction.

It was only activate the panel.

Thanks for the advice.