When a guest changes the dates of a stay, the booking panel may show the message "Sorry, this coupon has either expired or invalid" for a coupon that was already entered.
Why this happens. Guesty rejects the code if it has expired, or if the new stay no longer meets the coupon’s rules, such as the stay window, minimum nights, or usage limit. A code that is still valid for the new dates stays applied.
What you can do. The message reflects the coupon’s rules in Guesty, so check the coupon’s validity dates and conditions there.