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Understandable WCAG 3.3.3

3.3.3 Error Suggestion

If an input error is automatically detected and suggestions for correction are known, the suggestions are provided to the user, unless it would jeopardize the security or purpose of the content.

Level AA Moderate WCAG 2.0 (new) WCAG 2.1 WCAG 2.2

What this rule means

WCAG 3.3.3 builds on 3.3.1 by requiring not just error identification but also suggestions for how to fix the error, when the system can determine a correction. If a user enters an invalid email, the error message should suggest the correct format.

Exceptions exist for security-sensitive contexts (e.g., you should not suggest valid passwords or correct CAPTCHA answers).

Why it matters

Users with cognitive disabilities, learning disabilities, or limited technical knowledge may not know how to correct an error from the description alone. Providing actionable suggestions significantly improves form completion rates.

Error suggestions are also valuable for all users — they reduce frustration and form abandonment.

Related axe-core rules

There are no automated axe-core rules for error suggestion quality. Manual testing is required.

How to test

  • Trigger validation errors with various types of invalid input.
  • Check that error messages include specific suggestions for correction.
  • Verify suggestions are accurate and actionable.
  • Confirm that security-sensitive fields do not reveal valid values in suggestions.

How to fix

Bad practice

<!-- Vague error with no suggestion -->
<p class="error">Invalid date.</p>

<!-- Technical error code -->
<p class="error">Error: VALIDATION_FAILED_FORMAT</p>

Good practice

<!-- Specific error with suggestion -->
<p class="error" id="date-error">
  The date must be in DD/MM/YYYY format.
  Example: 15/03/2024
</p>

<!-- Email suggestion -->
<p class="error" id="email-error">
  Please enter a valid email address.
  Example: name@example.com
</p>

<!-- Select field suggestion -->
<p class="error" id="country-error">
  Please select a country from the list.
  You entered "Turkye" — did you mean "Turkey"?
</p>

Common mistakes

  • Error messages that only say "Invalid input" without explaining what is expected.
  • Technical error codes shown to end users.
  • Not suggesting the correct format for dates, phone numbers, or postal codes.
  • Suggesting valid passwords or security answers in error messages.

Resources