Bad value “0” for attribute “aria-rowspan” on element “div”: Zero is not a positive integer.

The aria-rowspan attribute is used in ARIA-based grid and table structures to indicate how many rows a cell spans. It serves a similar purpose to the rowspan attribute on native HTML <td> and <th> elements, but is designed for custom widgets built with ARIA roles like gridcell, rowheader, and columnheader within grid or treegrid structures.

According to the WAI-ARIA specification, the value of aria-rowspan must be a positive integer — a whole number greater than zero. A value of "0" is invalid because it implies the cell spans no rows, which is semantically meaningless. Note that this differs from native HTML’s rowspan attribute, where "0" has a special meaning (span all remaining rows in the row group). The ARIA attribute does not support this behavior.

This matters primarily for accessibility. Screen readers and other assistive technologies rely on aria-rowspan to convey the structure of custom grids to users. An invalid value of "0" can confuse assistive technology, potentially causing it to misrepresent the grid layout or skip the cell entirely. Ensuring valid values helps users who depend on these tools navigate your content correctly.

To fix this issue, determine how many rows the cell actually spans and set aria-rowspan to that number. If the cell occupies a single row, use "1". If it spans multiple rows, use the appropriate count. If you don’t need row spanning at all, you can simply remove the aria-rowspan attribute entirely, since the default behavior is to span one row.

Examples

Incorrect: aria-rowspan set to zero

<div role="grid">
  <div role="row">
    <div role="gridcell" aria-rowspan="0">Name</div>
    <div role="gridcell">Value</div>
  </div>
</div>

The value "0" is not a positive integer, so the validator reports an error.

Correct: aria-rowspan set to a positive integer

If the cell spans a single row, use "1" (or remove the attribute, since one row is the default):

<div role="grid">
  <div role="row">
    <div role="gridcell" aria-rowspan="1">Name</div>
    <div role="gridcell">Value</div>
  </div>
</div>

Correct: aria-rowspan for a cell spanning multiple rows

If the cell genuinely spans two rows, set the value accordingly:

<div role="grid">
  <div role="row">
    <div role="gridcell" aria-rowspan="2">Category</div>
    <div role="gridcell">Item A</div>
  </div>
  <div role="row">
    <div role="gridcell">Item B</div>
  </div>
</div>

Correct: removing the attribute when no spanning is needed

If the cell doesn’t span multiple rows, the simplest fix is to remove aria-rowspan altogether:

<div role="grid">
  <div role="row">
    <div role="gridcell">Name</div>
    <div role="gridcell">Value</div>
  </div>
</div>

When to use aria-rowspan vs. native HTML

If you’re building a data table, prefer native HTML <table>, <tr>, <td>, and <th> elements with the standard rowspan attribute. Native table semantics are automatically understood by browsers and assistive technologies without any ARIA attributes. Reserve aria-rowspan for custom interactive widgets (like spreadsheet-style grids or tree grids) where native table elements aren’t appropriate. The aria-rowspan value should always match the actual visual and structural layout of your grid to avoid confusing assistive technology users.

Learn more:

MDN Reference

MDN: aria-rowspan

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