The “headers” attribute on the element “td” refers to the ID X, but there is no “th” element with that ID in the same table.

The headers attribute creates explicit associations between data cells (td) and header cells (th) in complex tables. This is especially important for tables with irregular structures—such as those with merged cells or multiple header levels—where the browser cannot automatically determine which headers apply to which data cells.

When the validator reports this error, it means one or more IDs referenced in a td‘s headers attribute cannot be matched to any th element with that id in the same table. Common causes include:

• Typos — A small misspelling in either the headers value or the th element’s id.
• Missing id — The th element exists but doesn’t have an id attribute assigned.
• Removed or renamed headers — The th was deleted or its id was changed during refactoring, but the td still references the old value.
• Cross-table references — The th with the referenced id exists in a different <table>, which is not allowed.

Why this matters

This issue directly impacts accessibility. Screen readers use the headers attribute to announce which header cells are associated with a data cell. When a referenced ID doesn’t resolve to a th in the same table, assistive technology cannot provide this context, making the table confusing or unusable for users who rely on it. Broken headers references also indicate invalid HTML according to the WHATWG HTML specification, which requires that each token in the headers attribute match the id of a th cell in the same table.

How to fix it

1. Locate the td element flagged by the validator and note the ID it references.
2. Search the same <table> for a th element with a matching id.
3. If the th exists but has no id or a different id, add or correct the id attribute so it matches.
4. If the th was removed, either restore it or remove the headers attribute from the td.
5. Double-check for case sensitivity — HTML id values are case-sensitive, so headers="Name" does not match id="name".

Examples

Incorrect: headers references a non-existent ID

The first td references "product", but no th has id="product". The second th has id="cost", but the second td references "price" — a mismatch.

<table>
  <tr>
    <th>Product</th>
    <th id="cost">Price</th>
  </tr>
  <tr>
    <td headers="product">Widget</td>
    <td headers="price">$9.99</td>
  </tr>
</table>

Correct: each headers value matches a th with the same id

<table>
  <tr>
    <th id="product">Product</th>
    <th id="cost">Price</th>
  </tr>
  <tr>
    <td headers="product">Widget</td>
    <td headers="cost">$9.99</td>
  </tr>
</table>

Correct: multiple headers on a single td

In complex tables, a data cell may relate to more than one header. List multiple IDs separated by spaces — each one must correspond to a th in the same table.

<table>
  <tr>
    <th id="region" rowspan="2">Region</th>
    <th id="q1" colspan="2">Q1</th>
  </tr>
  <tr>
    <th id="sales">Sales</th>
    <th id="returns">Returns</th>
  </tr>
  <tr>
    <td headers="region">North</td>
    <td headers="q1 sales">1200</td>
    <td headers="q1 returns">45</td>
  </tr>
</table>

Tip: simple tables may not need headers at all

For straightforward tables with a single row of column headers, browsers and screen readers can infer the associations automatically. In those cases, you can omit the headers attribute entirely and avoid this class of error:

<table>
  <tr>
    <th>Product</th>
    <th>Price</th>
  </tr>
  <tr>
    <td>Widget</td>
    <td>$9.99</td>
  </tr>
</table>

Reserve the headers attribute for complex tables where automatic association is insufficient — such as tables with cells that span multiple rows or columns, or tables with headers in both rows and columns.

Learn more:

MDN Reference

MDN Web Docs: TR headers attribute

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MDN Reference

MDN Web Docs: <td>: The Table Data Cell element

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