The system version is 1.2.12. Coupon has been set before and it can work normally.
Yesterday, a new coupon was set up, and customers reported that the discount code was invalid. After self-testing, this is indeed the case.
I tried to modify the Per Coupon, Total Amount, and login status, etc., and every test showed the same error.
I can't check the source of the problem now, help me! Thank you!