Bad value “combobox” for attribute “role” on element “input”.

The combobox role represents a composite widget that combines a text input with a popup (typically a listbox) that helps the user set the value of the input. It’s a common pattern seen in autocomplete fields, search suggestions, and dropdown selects with type-ahead functionality.

The reason the validator rejects role="combobox" on <input> is rooted in how the HTML specification defines allowed ARIA roles for each element. An <input type="text"> already carries an implicit role of textbox, and the spec only permits a limited set of explicit roles on it (such as combobox in ARIA 1.2 contexts, but W3C HTML validation may still flag this depending on the validator’s conformance rules). When the validator encounters a role that isn’t in its allowed list for that element, it raises this error.

Why This Matters

• Standards compliance: Using roles outside the permitted set for an element violates the HTML specification, which can lead to unpredictable behavior across browsers and assistive technologies.
• Accessibility: Assistive technologies like screen readers rely on correct role assignments to convey the widget’s purpose. A misapplied role can confuse users who depend on these tools, making the combobox harder to navigate or understand.
• Browser interop: Browsers may handle conflicting implicit and explicit roles inconsistently, leading to different experiences across platforms.

How to Fix It

There are two main approaches depending on which ARIA pattern you follow:

Approach 1: ARIA 1.1 Pattern (Container as Combobox)

In the ARIA 1.1 combobox pattern, the role="combobox" is placed on a container element (like a <div>) that wraps the <input>. This is the approach most likely to pass W3C validation without issues.

Approach 2: ARIA 1.2 Pattern (Input as Combobox)

ARIA 1.2 moved the combobox role directly onto the <input> element itself, which is a simpler and more widely adopted pattern in practice. However, the W3C HTML Validator may still flag this as an error if its conformance rules haven’t been updated to reflect ARIA 1.2. If passing validation is a strict requirement, use Approach 1.

Examples

❌ Incorrect: role="combobox" directly on <input>

This triggers the validation error:

<input type="text" role="combobox" aria-autocomplete="list">

✅ Correct: ARIA 1.1 pattern with container element

The role="combobox" is placed on the wrapping <div>, and the <input> inside it handles text entry:

<div role="combobox" aria-haspopup="listbox" aria-owns="suggestions" aria-expanded="false">
  <input type="text" aria-autocomplete="list" aria-controls="suggestions">
</div>
<ul id="suggestions" role="listbox" hidden>
  <li role="option" id="opt-1">Apple</li>
  <li role="option" id="opt-2">Banana</li>
  <li role="option" id="opt-3">Cherry</li>
</ul>

Key attributes explained:

• role="combobox" on the <div> defines the overall widget for assistive technologies.
• aria-haspopup="listbox" tells screen readers that this widget has a popup of type listbox.
• aria-owns="suggestions" establishes an ownership relationship between the combobox and the listbox, even if they aren’t parent-child in the DOM.
• aria-expanded="false" indicates whether the popup is currently visible. Update this to "true" via JavaScript when the list is shown.
• aria-autocomplete="list" on the <input> signals that suggestions will be presented in a list as the user types.
• aria-controls="suggestions" on the <input> links it to the listbox it controls.

✅ Correct: ARIA 1.2 pattern using <input> with role="combobox" (if validation is not strict)

If your project follows ARIA 1.2 and you can tolerate or suppress the validation warning, this pattern is widely supported by modern browsers and screen readers:

<label for="fruit">Choose a fruit</label>
<input
  id="fruit"
  type="text"
  role="combobox"
  aria-autocomplete="list"
  aria-expanded="false"
  aria-controls="fruit-list"
  aria-haspopup="listbox">
<ul id="fruit-list" role="listbox" hidden>
  <li role="option" id="fruit-1">Apple</li>
  <li role="option" id="fruit-2">Banana</li>
  <li role="option" id="fruit-3">Cherry</li>
</ul>

This is the pattern recommended by the WAI-ARIA Authoring Practices Guide and is the most commonly implemented in modern component libraries. If validation compliance is required, wrap the input in a container and move the role="combobox" there as shown in Approach 1.

Whichever approach you choose, remember that ARIA attributes alone don’t create behavior — you’ll need JavaScript to toggle aria-expanded, manage focus, handle keyboard navigation, and update aria-activedescendant as the user moves through options.

Learn more:

MDN Reference

ARIA: combobox role

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MDN Reference

HTML input element - MDN Web Docs

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MDN Reference

The role attribute - MDN Web Docs

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