Accessibility finding
An accessibility overlay changes what the scanners find
Accessibility Warning Severity: High
Part of the audit A script overlay hides problems that remain in the source. Finding id: accessibility.overlayVsSource.
What it costs you
The page with the overlay and the page without it do not have the same failures, so visitors get different pages.
What to do
Worth checking with a screen reader user; we assume the source has to work without the overlay. Fix each failure where it comes from.
What it checks
- Accessibility overlay detected
- Failures appear only without overlay
- Overlay introduces new failures
How to fix it
Fix the source, then review the overlay
- Take the failures that appear only without the overlay and fix them in the site's own templates.
- Take the failures that appear only with the overlay to the overlay's supplier, or switch off the feature that causes them.
- When the list without the overlay is empty, decide whether to keep the overlay.
How to check: Recrawl: the run with the overlay blocked and the normal run report the same elements.
A real case
The US Federal Trade Commission found that accessiBe's claim that its overlay could make any website comply with WCAG was not supported. In January 2025 the company agreed to pay 1 million dollars.
Thresholds
| Name | Default | Meaning |
|---|---|---|
min_scanners | 2 | How many scanners must report the same element before the difference counts as a failure. |
How to verify by hand
A screen reader user; overlays often fail them.
What this relies on
The source must conform on its own; an overlay is temporary.