F20Documented failure WCAG 1.1.1 WCAG 4.1.2 Level A Partly scanner-detectable

Do not let text alternatives fall out of date

F20 is a documented failure filed under two rules, non-text content and name, role and value, so it covers stale alt text and stale accessible names alike. The test is one sentence and worth memorizing. If the text can no longer be used in place of the content without losing information or function, it has stopped being an alternative. Nothing about that turns on scripting. Three shapes produce it. A chart image updated to October with alt text still describing September. Home page photographs rotating daily while their alt text stays put. A script swapping an image source and leaving the alt attribute behind. The first two need no JavaScript at all, and they are what ordinary marketing sites produce, which is why a code review never finds them.

How we find it in an audit

Reviewers interact with every dynamic image and every icon control and listen to what the name becomes. A play button that still says Play after playback started is the same failure as a stale chart. Then we go at it from the other direction, comparing alt text against images that get replaced on a schedule, which is a content job rather than a code one. Automated tools see one moment in time and can confirm alt text exists. Whether it is still true is a question about two moments.

How affected users experience it

The cruelty of this failure is that it looks like it works. There is alt text. It is descriptive, it is well written, and it belongs to an image that is no longer there. A blind reader gets September's numbers presented as October's and has no reason to doubt them, because nothing sounds broken. On a control it costs an action rather than a fact. The button says Play, so they press it, and the thing they were listening to stops.

Passes vs. fails

Passes: alt text names the product. Fails: the file name is all there is.

Passes

slide.src = slides[i].url;
slide.alt = slides[i].description;
// The same edit that changes the picture changes the words.

Fails

slide.src = slides[i].url;
// slide.alt still describes slide 1, three slides later.

How this gets tested

The W3C publishes test rules that define what a checker looks for here.

Element marked as decorative is not exposedA tool can check this
Image accessible name is descriptiveA tool finds candidates, you decide
Image button has non-empty accessible nameA tool can check this
Image has non-empty accessible nameA tool can check this
Link has non-empty accessible nameA tool can check this
Object element rendering non-text content has non-empty accessible nameA tool can check this
SVG element with explicit role has non-empty accessible nameA tool can check this
Image not in the accessibility tree is decorativeA tool can check this
ARIA attribute is defined in WAI-ARIAA tool can check this
ARIA state or property has valid valueA tool can check this
Element with role attribute has required states and propertiesA tool can check this
Form field has non-empty accessible nameA tool can check this
Role attribute has valid valueA tool can check this
ARIA state or property is permittedA tool can check this
Button has non-empty accessible nameA tool can check this
Element with aria-hidden has no content in sequential focus navigationA tool can check this
Element with presentational children has no focusable contentA tool can check this
Menuitem has non-empty accessible nameA tool can check this
Summary element has non-empty accessible nameA tool can check this
Iframe element has non-empty accessible nameA tool can check this
Iframe elements with identical accessible names have equivalent purposeA tool finds candidates, you decide

The other techniques filed under this rule

39 guides on this site are filed under 1.1.1 Non-text Content. W3C documents this one as a failure of that rule, so it describes a way the rule gets broken rather than a way to pass it.

This guide is our interpretation of W3C technique F20: Failure of Success Criterion 1.1.1 and 4.1.2 due to not updating text alternatives when changes to non-text content occur. W3C publishes its techniques as guidance rather than as the standard, and says so on every one of them. The success criterion is what conformance is measured against, and a technique is one documented way to meet it.