Invalid alone does not distinguish a typo from an excluded gift card.
Coupon errors with explanations and preserved baskets
Explain whether a code is unknown, expired or ineligible. Preserve the basket and typed code for correction.
Research context: Baymard · Inline form validation ↗
Provide only explanations the server can confirm. Do not disclose private campaigns or internal restrictions.
Try the pattern
Task and expected result
- 01
Use WRONG: see a specific error and retain all basket lines.
- 02
Change to LAB10: discount only mugs.
- 03
Remove the code: restore the total without removing items.
How to investigate value
Measure confirmed, deduplicated outcomes per eligible checkout start. Define paid orders and accepted credit orders separately.
Watch for side effects
Payment errors, duplicate orders, incorrect totals, unclear arrival dates and discount cost. A pay click is only an attempt.
This is a proposed investigation, not a measured result. Choose one hypothesis and define the audience before testing.
Build a measurement plan for this concept ↗