SQLSTATE[42000]: Syntax error or access violation: 1055 Expression #2

hi i got this error when trying to make a chart

SQLSTATE[42000]: Syntax error or access violation: 1055 Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'klinik_bersalin.ibu.created_at' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

and this is my controller

 public function index()
    {
        $ibu = Ibu::select(DB::raw("COUNT(*) as count"), DB::raw("MONTHNAME(created_at) as month_name"))
                    ->whereYear('created_at', date('Y'))
                    ->groupBy(DB::raw("Month(created_at)"))
                    ->pluck('count', 'month_name');

        $labels = $ibu->keys();
        $data = $ibu->values();

        return view('chart', compact('labels', 'data'));
    }

How do i resolve it? Thank you