Table column N established by element “th” has no cells beginning in it.

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 <td> or <th> element has a colspan attribute value that extends beyond the total number of columns defined in the <tbody> section.

HTML tables must have rows with a consistent number of columns within each <thead>, <tbody>, or <tfoot> group. If a cell uses the colspan attribute to span more columns than exist in the current row group, the table becomes semantically incorrect and fails validation.

Example of the Issue

<table>
  <tbody>
    <tr>
      <td>Cell 1</td>
      <td>Cell 2</td>
    </tr>
    <tr>
<!-- Invalid: colspan="3" but only 2 columns in tbody -->

    </tr>
  </tbody>
</table>

How to Fix

Ensure that the maximum number of columns in any row (considering colspan) within a <tbody> does not exceed the columns defined by the longest row in that group.

Corrected Example

<table>
  <tbody>
    <tr>
      <td>Cell 1</td>
      <td>Cell 2</td>
      <td>Cell 3</td>
    </tr>
    <tr>
      <td colspan="3">Spans all columns</td>
    </tr>
  </tbody>
</table>

Or, if you only need two columns:

<table>
  <tbody>
    <tr>
      <td>Cell 1</td>
      <td>Cell 2</td>
    </tr>
    <tr>
      <td colspan="2">Spans two columns</td>
    </tr>
  </tbody>
</table>

Adjust the column count by either increasing the number of cells in each row or reducing the value of colspan as appropriate for your table structure.

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>