instagram profil picture full size invalid url signature?

a few days ago i was able to fetch inta profile pic in my android app by remove the part from vp/ to /t51 {vp/…}/t51.. from the pic URL….jpg

but it doesn’t work !!

and change the resolution from s150x150 to s720x720 ,and it worked fine but now i still get “invalid url signature”, so I think Instagram has added signature to their URL

I don’t know what’s happened with instagram,so can someone help meto find a solution for this problem? Or an alternate method. Thanks