What're values of your "month" column that you intended to sort by?

Since the "month" column can't be sorted by its value, we need another column based on its value, which can be sorted. Pls try this code:

    DataTables::create(array(
        ...
        "columns" => array(
        	...
            "standardMonth" => array(
            	"visible" => false, //no need to show this column
            	"formatValue" => function($row, $row, $colKey) {
            		$month = $row["month"];
            		$standardMonth = convertMonthYear($month); // use DateTime class to convert $month to standard date value, such as "2021-01-31", or just a simple year month "2021-01"
            		return $standardMonth;
            	}
            ),
        	"month" => array(
        		"data-order" => "standardMonth", //order this column by "standardMonth" column
        	)
        )
    ));

Let us know if you have any further question. Rgds,

Oh, I made a mistake. Pls change this line:

    "formatValue" => function($row, $row, $colKey) {

to:

    "formatValue" => function($value, $row, $colKey) {

Tks,

I forgot to mention, this line is a mocked up code:

    $month = $row["month"];
    $standardMonth = convertMonthYear($month);

It meant you'd have to write your own code to convert from your month and/or year to a standard date format string like "2021-01-31", which we use to sort by. I don't know exactly your original month date value so I can't give specific guidance.