ArgumentException: Path is empty while saving data in an XML

enter code herehello , i've been stuck with this for days , can someone give me a little insight on what is causing this .
when ever i trigger Save() by hitting a button ,i get this error , i would like to highlight that data are saved on pc even when this error popup , but on android nothing get saved ,

here is the error i get

ArgumentException: Path is empty System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean anonymous, FileOptions options) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.IO/FileStream.cs:209) System.IO.FileStream..ctor (System.String path, FileMode mode) (wrapper remoting-invoke-with-check) System.IO.FileStream:.ctor (string,System.IO.FileMode) JetpackXmlManager.Save () (at Assets/Resources/JetpackXmlManager.js:45) BoostEUConsumptionProgress.Check () (at Assets/BoostEUConsumptionProgress.js:128) UnityEngine.GameObject:SendMessage(String) ConfirmPayment:Confirm() (at Assets/ConfirmPayment.js:8) UnityEngine.EventSystems.EventSystem:Update()

 public class JetpackXmlManager extends  MonoBehaviour {
  
     function Awake(){
  
         if(Application.platform==RuntimePlatform.Android)
             RootFolder ="jar:file://" + Application.persistentDataPath  + "!/assets/XmlFiles/JetpacksDB.xml";
  
         else
             RootFolder =   Application.dataPath + "/StreamingAssets/XmlFiles/JetpacksDB.xml";
    
  
         Open();
     }
  
         // save function
        public function Save(){
  
            var MySerializer :XmlSerializer = new XmlSerializer(typeof(SavedItems) );
            var MySaveFile :FileStream = new FileStream(RootFolder,FileMode.Create);
                MySerializer.Serialize(MySaveFile,JetpackDB);
                MySaveFile.Close();
  
        }
         // Open function
        public function Open(){
  
  
            var MySerializer :XmlSerializer= new XmlSerializer(typeof(SavedItems));
            var linkstream : WWW  ;
            if(Application.platform==RuntimePlatform.Android)   linkstream = new WWW( "jar:file://"+Application.persistentDataPath +"!/assets/XmlFiles/JetpacksDB");
  
        else    linkstream = new WWW("file:///" + Application.dataPath  + "/StreamingAssets/XmlFiles/JetpacksDB");
    
            yield  linkstream;
            if (linkstream.isDone == true) {
                var MySaveFile  = new StringReader(linkstream.text);
  
                JetpackDB= MySerializer.Deserialize(MySaveFile) as SavedItems;
                MySaveFile.Close();
  
            }
  
  
  
  
        }
 }