console error "Cannot read property mData of undefined"..??

These can be the possible issues related to this error :

1.Table must contain <thead> and <tbody> tags, otherwise it throws this error, for example below table will throw error

<table id="erroTable">
    <tr>
        <th>Test</th>
        <th>Test2</th>
    </tr>
    <tr>
        <td>Data-1</td>
        <td>Data-2</td>
    </tr>
</table>

<!--Error may occur because of no tbody and thead defined-->

2. Mismatched number of columns(this table will also throw error) :

<table id="ErrorTable">
    <thead>
        <tr>
            <th>Test</th>
            <th>Test2</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>Ok-1</td>
            <td>ok-2</td>
            <td>Error because of this extra value</td>
        </tr>
    </tbody>
</table>

3.It can also occur if you have table arguments for 'aoColumns':[..] which don't match the correct number of columns, means may be you have defined aoColumns for 4 columns but there are only 2 columns in table.

4.Could occur due to Duplication of table Id(two table with same Ids)

Anyone of the above solutions should work.

Most of the times, this error occurs when number of columns in <thead> <th> is different than <tbody> <tr> <td>

But it can also occur if number of columns in 'aoColumns':[ ] does not have the correct number of columns.

For example, this configuration will not work

<table id="datatable">
    <thead>
        <tr>
            <th>col 1</th>
            <th>col 2</th>
        </tr>
    </thead>
    <tbody>
        <td>data 1</td>
        <td>data 2</td>
    </tbody>
</table>
<script>
        var datTable = $('#datatable');
        datTable.DataTable({
            'order': [[ 1, 'desc' ]],
            'aoColumns': [
                null,
                null, 
                null,
                null,
                {
                    'bSortable': false
                }
            ]
        });
</script>

But this will work:

<table id="datatable">
    <thead>
        <tr>
            <th>col 1</th>
            <th>col 2</th>
        </tr>
    </thead>
    <tbody>
        <td>data 1</td>
        <td>data 2</td>
    </tbody>
</table>
<script>
        var datTable = $('#datatable');
        datTable.DataTable({
            'order': [[ 1, 'desc' ]],
            'aoColumns': [
                null,
                {
                    'bSortable': false
                }
            ]
        });
</script>

Hope this helps.