Table cell spans past the end of its row group established by a “tbody” element; clipped to the end of the row group.

A <table> contains a <tr> row that has less <td> columns than the column count established by the first row. Check the table to ensure all rows have the same number of columns.

For example, in the following table, the first <tr> row defines that it’s 2 columns wide, but the second <tr> row tries to use only 1 column:

<table>
<!-- This first row sets the table as 2 columns wide -->

  <tr>
    <td>First</td>
    <td>Second</td>
  </tr>

<!-- This second row has only 1 column -->

  <tr>
    <td>Wrong</td>
  </tr>
</table>

The <table> element does not accept a height attribute. Use CSS instead.

A td (table cell) start tag must be placed inside a tr (table row) within a table.

The td element represents a cell of a table that contains data. According to HTML specifications, a td must be a child of a tr, which in turn must be a child of a table. Placing a td directly outside a tr or outside a table is invalid and causes the “stray start tag ‘td’” error in the W3C Validator.

Incorrect usage:

<table>
  <td>Cell data</td>
</table>

In the above example, the td is not inside a tr.

Correct usage:

<table>
  <tr>
    <td>Cell data</td>
  </tr>
</table>

Here, the td is nested inside a tr, which is correctly within a table. This will resolve the validation error.

A <table> contains an incoherent number of columns on one of its rows. Check the structure of the table to find the invalid row.

For example, in the following table, the first <tr> row defines that it’s 2 columns wide, but the second <tr> row tries to use 5 columns by means of a colspan attribute:

<table>
<!-- This first row sets the table as 2 columns wide -->

  <tr>
    <td>First</td>
    <td>Second</td>
  </tr>

<!-- This second row tries to use 5 columns -->

  <tr>
    <td colspan="5">Wrong</td>
  </tr>
</table>

A td element’s headers attribute must reference the ID of a th element within the same table.

The headers attribute is used to define explicit associations between data cells (td) and header cells (th) by referencing header cell IDs. For valid markup, every ID referenced in the headers attribute must exist as a th element’s id within the same table. This helps users—especially those using assistive technology—understand which header(s) apply to each data cell.

For example, if a td references headers="table_header_1", there must be a th id="table_header_1" present. If it’s missing or mistyped, you’ll get the validator error you described.

Correct pattern:

<table>
  <tr>
    <th id="table_header_1">Header 1</th>
    <th id="table_header_2">Header 2</th>
  </tr>
  <tr>
    <td headers="table_header_1">Row 2, Column 1</td>
    <td headers="table_header_2">Row 2, Column 2</td>
  </tr>
</table>

Incorrect pattern (missing th ID):

<table>
  <tr>
    <th>Header 1</th>
    <th id="table_header_2">Header 2</th>
  </tr>
  <tr>
    <td headers="table_header_1">Row 2, Column 1</td>
    <td headers="table_header_2">Row 2, Column 2</td>
  </tr>
</table>

To resolve the error, ensure every value in a td‘s headers attribute matches the id of a th element in the same table.