The “textbox” role is unnecessary for element “textarea”.

A <textarea> element already has the ARIA role textbox, so role="textbox" on it repeats what the browser tells assistive technologies anyway.

Browsers expose every <textarea> as a multi-line text box, together with its label, value and placeholder. Adding the role changes nothing, which is why the validator reports it as a warning and not as an error.

The attribute is often left over from a chat or comment box that started as a <div contenteditable>. A <div> has no role of its own and does need role="textbox", but a real <textarea> doesn't. Don't swap the role for another one either: textbox is the only role a <textarea> accepts, and the validator rejects others such as searchbox or combobox with a "Bad value" error. Remove the attribute.

Invalid example

<form action="/chat">
  <label for="message">Message</label>
  <textarea id="message" name="message" rows="3" role="textbox"></textarea>
  <button type="submit">Send</button>
</form>

Valid example

<form action="/chat">
  <label for="message">Message</label>
  <textarea id="message" name="message" rows="3"></textarea>
  <button type="submit">Send</button>
</form>

Learn more:

MDN Reference

MDN - ARIA textbox role

→

MDN Reference

MDN - the textarea element

→

W3C Reference

W3C - ARIA in HTML

→