Coupon code custom error message

Hello,
Is there a way to set coupon code error? That way, if a customer enters expired coupon or inactive coupon, they will be notified? The way it is now, nothing happens and I know customers will be frustrated and angry

Hi,

That is already the case. The error message is already different based on what prevented the system to use the coupon.
And you can always customize these error messages with translation overrides:
www.hikashop.com/support/download/languages.html#modify