18. Incorrect column count

If a table is loaded where the number of columns defined by the header and used in the body do not match, the error:

Incorrect column count

will occur when the table is loaded.

Meaning

DataTables requires that the number of columns defined in the table header match the number of columns that are used in the table body. If they mismatch, not only will DataTables throw an error, but the HTML document would also be invalid.

Consider the following:

<table>
    <thead>
        <tr>
            <th>...</th>
            <th>...</th>
            <th>...</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>...</td>
            <td>...</td>
        </tr>
        ...
    </tbody>
</table>

In this case, the header defines three columns but the first row in the table body only defines two columns. This error would be triggered when initialising DataTables on such a table.

The converse is also true:

<table>
    <thead>
        <tr>
            <th>...</th>
            <th>...</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>...</td>
            <td>...</td>
            <td>...</td>
        </tr>
        ...
    </tbody>
</table>

In this case, the body row has more columns than the header, also triggering this error.

These two cases are the most simple type, but the error can also occur when complex headers (i.e. those with colspan and rowspan attributes on the cells) are used. In such a case the same rules apply - the number of columns defined in the header must match those used in the table body rows.

Additionally, DataTables does not support colspan or rowspan attributes on cells in the table body.

Resolution

To resolve this issue, make sure that the number of columns in the table header match those in the table body: