Loading Bitmap Failed on Berlin

I have a problem migrating a process from XE8 to Berlin 10.1

On XE8 work fine on Berlin a get a "Loading Bitmap Failed" error

i have a Datasnap Rest server with a method

function TSM.Downloafile(): TStream;
var s:TFileStream;
begin
    s := TFileStream.Create('C:\image1.jpg',fmOpenReadWrite);
    Result := s
end;

on xe8 i get the stream fine i can see the image using a browser

http://localhost:105/datasnap/rest/TSM/Downloafile

on Berlin when i try show the image i get this string [122,216,255,244,0,15,......]

Loading Bitmap Failed