Laravel Error : Method save does not exist

You should always check if query returns null. Use is_null or empty():

foreach ($servicedata as $key => $val) {
    $detailservice = DetailServiceOrder::find($request->detail_service_id);
    if (!is_null($detailservice)) {
        $detailservice->sales_order_id = $request->sales_order_id;
        $detailservice->service_id = $input['service_id'][$key];
        $detailservice->order_type = $input['order_type'][$key];
        $detailservice->select_plan = $input['select_plan'][$key];
        $detailservice->qty = $input['qty'][$key];
        $detailservice->unit_price = $input['unit_price'][$key];
        $detailservice->note = $input['note'][$key];
        $detailservice->save();
    }
}

foreach ($employeedata as $key => $val) {
    $detailemployee = DetailEmployeeOrder::find($request->detail_employee_id);
    if (!is_null($detailemployee)) {
        $detailemployee->sales_order_id = $request->sales_order_id;
        $detailemployee->employee_id = $input['emp_id'][$key];
        $detailemployee->mandays = $input['mandays'][$key];
        $detailemployee->save();
    }
}

Maybe try different approach?

public function update(Request $request, $id)
{

 /*
 <---- this line is my another code ---->
 */

   $input = Input::all();
    $servicedata = $input['service_id'];
    $employeedata = $input['emp_id'];

    foreach ($servicedata as $key => $val) {
        DetailServiceOrder::where('detail_service_id', $request->detail_service_id)->
            update(['sales_order_id' = $request->sales_order_id, 
                    'service_id' = $input['service_id'][$key], 
                    'sales_order_id' = $request->sales_order_id, 
                    'order_type' = $input['order_type'][$key], 
                    'select_plan' = $input['select_plan'][$key], 
                    'qty' = $input['qty'][$key], 
                    'unit_price' = $input['unit_price'][$key], 
                    'note' = $input['note'][$key] ]);            
    }

    foreach ($employeedata as $key => $val) {
        DetailEmployeeOrder::where('detail_employee_id', $request->detail_employee_id)->
            update(['sales_order_id' = $request->sales_order_id,                         
                    'employee_id' = $input['emp_id'][$key], 
                    'mandays' = $input['mandays'][$key] ]);                 
    }
}

In this case you don't need to check if record exists because it doesn't use save() method.

For more help check this.

Hope it helps

$detailservice is null i think, you should check if it null or not

if ( ! $detailservice) continue;

I had the same problem, in my case is was just because i use ->get() instead of ->first() like a dummy, obviously there is no method save on a collection... So i reply if someone see this question like me in my research