Laravel ajax AJAX error: Internal Server Error 500

I have used this in my html part:

<meta name="csrf-token" content="{{ csrf_token() }}" />

In script I have done:

$(document).ready(function() {
    $(document).on('change','#user_id', function() {
        try {
            var user_id = $(this).val();
            $('#balance_amount').val("Loading response...");
            $.ajaxSetup({
                beforeSend: function(xhr, type) {
                    if (!type.crossDomain) {
                        xhr.setRequestHeader('X-CSRF-Token', $('meta[name="csrf-token"]').attr('content'));
                    }
                },
            });
            $.ajax({
                url: "{{ URL::to('/getEmpBalance')}}",
                method: 'post',
                data: {
                    'user_id' : user_id
                },
                success: function(result) {
                    console.log("Success "+result);
                    $('#balance_amount').val(result);
                },
                error: function(e, jqXHR, textStatus, errorThrown) {
                    // console.log("Error "+e);
                    // console.log(JSON.stringify(jqXHR));
                    console.log("AJAX error: " + textStatus + ' : ' + errorThrown);
                    $('#transaction_description_editor').html(e);
                }
            });
            //console.log(user_id);
        } catch (e) {
            // console.log(e);
            // console.log(warning);
            // console.log(text);
        }
    });
});

But after sending ajax post request it gives error and when I checked, I found

{message: "Method App\Http\Controllers\AjaxController::getEmployeeBalance does not exist.",…} exception: "BadMethodCallException" file: "/home/studyn5/exp.studynextglobal.com/vendor/laravel/framework/src/Illuminate/Routing/Controller.php" line: 68 message: "Method App\Http\Controllers\AjaxController::getEmployeeBalance does not exist." trace: [{function: "__call", class: "Illuminate\Routing\Controller", type: "->"}, {,…}, {,…}, {,…}, {,…},…]

But it my ajax Controller I have mentioned this method

public function getEmployeeBalance(Request $request) {
    $user_id = $request->user_id;
    $exp_amount = DB::table('exp_amounts')
                        ->where('user_id', $user_id)
                        ->orderBy('created_at','desc')
                        ->first();

    if ($exp_amount === null) {
        echo "0";
    }
    else {
        $balance_amount = $exp_amount ->total_amount;
        echo $balance_amount;
    }   
}