WCAG 3.3.6 — Error Prevention (All)

What this requires

For web pages that require the user to submit information, at least one of the following is true:

Reversible: submissions are reversible.
Checked: data entered is checked for input errors with a chance to correct.
Confirmed: a mechanism is available to review, confirm, and correct before submission.

The AAA criterion applies to all user submissions, not just 3.3.4's legal / financial / data subset.

How AI coding tools fail this

Same failure shapes as 3.3.4, but for the broader form universe. AI tools generate forms that submit immediately with no review and no undo, regardless of consequence weight.

The AAA-specific failure: teams that have implemented review for checkout and account-deletion (covered by 3.3.4) and missed it for contact forms, comment submissions, and survey responses.

Passing examples

A preview step before posting, plus a brief edit window after:

<>
  <textarea
    value={body}
    onChange={(e) => setBody(e.target.value)}
  />
  {preview ? (
    <>
      <article>{renderMarkdown(body)}</article>
      <button onClick={() => setPreview(false)}>Edit</button>
      <button onClick={post}>Post</button>
    </>
  ) : (
    <button onClick={() => setPreview(true)}>Preview</button>
  )}
</>

// After posting, a brief undo window:
{justPosted && (
  <div role="status" aria-live="polite">
    Comment posted.{" "}
    <button onClick={undo}>Undo</button>
  </div>
)}

Edge cases

AAA scope. Most projects target AA's 3.3.4 — confirmable destructive actions only. 3.3.6 extends the requirement to all submissions.
"Reversible" can be a short undo window rather than full undo. A 30-second "undo send" timer is reversible.
Forms with autocomplete-confirmable data (a contact email copied from the user profile) satisfy the "checked" path through format validation plus a review screen.
Combine paths. A review screen plus inline validation plus an undo window is the safest mix.
Side-effect-free submissions (a search query) probably don't trigger this criterion — they don't carry the consequence weight.

How Jeikin handles this

The 3.3.4 scanner findings extend to 3.3.6 for AAA-targeting projects. The dashboard maps each form to both criteria and records the review or undo mechanism per form.

References

W3C — Understanding 3.3.6 Error Prevention (All) (opens in new tab)