Coupon code is not valid
Applying a coupon at checkout returned Coupon code is not valid. (premium.couponInvalid / checkout-coupon).
Why this happens
Typo, expired/disabled coupon, wrong product scope, or usage limit reached. Distinct from admin A coupon with this code already exists (create duplicate) and from empty-field prompts.
Diagnose and fix
1. Member: re-check spelling; try again; confirm the promo is still active.
2. Admin: open the coupon — enabled, dates, plan/product rules, max redemptions.
3. Distinct from Coupon could not be applied (apply API soft failure).
4. Remove the code and pay full price if the promo ended.