Error Prevention (Legal, Financial, Data)
For pages that cause legal commitments or financial transactions or modify user data, submissions must be reversible OR validated for input errors with an opportunity to correct OR confirmable before final commitment.
What it requires
WCAG 3.3.4 protects users with cognitive disabilities, motor impairments, or simple inattention from accidentally committing irreversible transactions. Three implementation paths satisfy the criterion: (1) make submissions reversible (cancel within N hours), (2) validate inputs and require correction before submit, (3) require an explicit confirmation step before final commit.
For ecommerce checkout, the standard implementation is path 3: a final review step where the user confirms address, payment method, and total before clicking "Place Order".
Common Shopify failure
Custom Hydrogen checkout that submits the order as soon as the user clicks "Pay" without showing an order summary + confirmation. Standard Shopify checkout passes by default; custom Plus checkout-extension flows can regress this.
How to fix it
AccessComply audits checkout flows for the confirmation step + reversibility window. Flags custom flows missing the order-summary review step.
Primary source: W3C — WCAG 2.0 Understanding 3.3.4