Bad value “” for attribute “colspan” on element “td”: The empty string is not a valid positive integer.

An empty colspan on a <td> is invalid, because the attribute takes the number of columns the cell spans, a whole number from 1 to 1000.

Both colspan="" and a bare colspan with no value get this error. A value made only of spaces, like colspan=" ", gets a different one that starts with "Expected a digit".

Empty attributes like this usually come from a table builder in a CMS, or from a template that prints colspan="{{ cell.colspan }}" on every cell, whether or not the cell spans anything. The same templates often print rowspan="" too, which gets its own error saying "non-negative integer" instead, because rowspan also accepts 0.

Browsers treat an empty colspan as 1, the same as leaving the attribute out, so the table looks the same once you remove it. Change the template to print colspan only when the cell spans two or more columns.

Invalid example

<table>
  <tr>
    <th>Plan</th>
    <th>Price</th>
  </tr>
  <tr>
    <td colspan="">Basic</td>
    <td colspan="">$10</td>
  </tr>
  <tr>
    <td colspan="2">Prices include tax.</td>
  </tr>
</table>

Valid example

<table>
  <tr>
    <th>Plan</th>
    <th>Price</th>
  </tr>
  <tr>
    <td>Basic</td>
    <td>$10</td>
  </tr>
  <tr>
    <td colspan="2">Prices include tax.</td>
  </tr>
</table>

Learn more:

MDN Reference

MDN Web Docs: The table data cell element

→

WHATWG Spec

HTML Standard: Tabular data

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