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From: Steve Green
Date: Jun 16, 2025 10:23AM

I have given this a great deal of thought, helped greatly by Adrian Roselli's article at https://adrianroselli.com/2023/04/exposing-field-errors.html. My conclusion is that the “aria-describedby” attribute is not suitable for use as a live region with respect to conformance with success criterion 4.1.3. I will therefore not open an issue on the WCAG repo at this stage.



For those who care about this arcane topic, the arguments for and against are:



For

* Section 4.8.1 of the W3C Core Accessibility API Mappings 1.2<https://www.w3.org/TR/core-aam-1.2/#mapping_events_state-change> specification states that changes in the value of the “aria-describedby” attribute must be exposed as an event via the accessibility API (which would trigger the live region). This is currently a draft specification.
* The technique works with NVDA screen reader and Chrome on Windows 11.
* The technique should work with other Chromium-based browsers such as Microsoft Edge, Opera and Samsung Internet.



Against

* This use of the “aria-describedby” attribute is not included in any of the Sufficient Techniques for success criterion 4.1.3.
* Section 5.8.1 of the W3C Core Accessibility API Mappings 1.1<https://www.w3.org/TR/core-aam-1.1/#mapping_events_state-change> specification does not include the “aria-describedby” attribute. This is the current version of the specification. We do not know when v1.2 will be published or whether it will be modified before publication.
* The technique is unlikely to currently work with other browsers such as Firefox and Safari. We do not know if or when they will adopt the W3C Core AAM 1.2 specification.
* It is possible that the technique only works if the website automatically moves the focus to the form control that is in error.
* We have not tested the technique with any other Chromium-based browsers or any other assistive technologies. In 2023, Adrian Roselli tested this and some other techniques with a large number of browsers and assistive technologies. His results are in line with our expectations.



Steve