WCAG 2.0 · Level AA · Understandable
3.3.4 Error Prevention (Legal, Financial, Data)
Manual verification
How to validate 3.3.4 by hand
For legal commitments, financial transactions, or user-controlled data changes, check the required safeguards before final submission.
Start with the extension result
Reopen the reported URL and reproduce the same state (for example, after expanding a menu or submitting a form). Use the result’s Highlight action when available, or its affected-element details and CSS selector, to find the reported content. Apply the checks below to that content and its context. If the element or state has changed, rescan and record that difference before deciding whether the finding still applies.
- Run a representative transaction or data-change workflow through its final review step.
- Check whether the action is reversible, checked for errors with a chance to correct, or presented for review/confirmation before completion.
- Test whether the review identifies the amount, recipient, changed data, or legal commitment accurately and allows correction.
Evidence to record
Record the transaction/data action, safeguard provided, review content, and whether an error can be corrected before finalization.
Scope and exceptions
This applies to the specified high-impact actions, not ordinary forms. Confirm which safeguard is used and whether an applicable exception is documented.
Record the review outcome
- Confirmed: the recorded evidence shows the requirement is not met in the tested page state, and no applicable exception explains it.
- Not reproduced: the reported issue is absent in the current state. Record the URL, state, and affected element you checked; this does not prove other pages or states conform.
- Needs more review: evidence is incomplete, the content requires human judgment, or an exception is uncertain. Record what remains to be checked instead of treating it as a pass.