WCAG 2.0 · Level AA · Understandable
3.3.3 Error Suggestion
When an input error is automatically detected and a correction suggestion is known, provide that suggestion unless doing so would jeopardize the security or purpose of the content.
Manual verification
How to validate 3.3.3 by hand
When an input error is detected and a safe correction is known, check whether a correction suggestion is provided.
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.
- Enter invalid values for fields with known formats or constrained choices.
- Read the resulting error and determine whether the expected format, valid range, or a safe suggested correction is explained.
- Check whether the suggestion would expose sensitive information or compromise the purpose of the task.
Evidence to record
Record the invalid input, known correction, message, and any security/purpose reason for withholding the suggestion.
Scope and exceptions
A suggestion is not required when no correction is known or when providing it would jeopardize security or content purpose. Clear error identification is still required separately.
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.
Why it matters
A specific correction suggestion can help a person recover from an input error without guessing what went wrong or repeatedly trying different values.
Examples and distinctions
Known format
If a date is rejected because the expected format is known, explain the required format (for example, day, month, and year order).
Unrecognized value
If a submitted value does not match known choices and a safe correction is known, offer a useful suggestion.
Security or purpose exception
Do not reveal a suggestion when doing so would compromise security or defeat the purpose of the content; check the exception against the actual situation.