HttpRuntime CacheInternal NULL reference exception while reading user sessions (Reflection)

After some updates on our windows servers(2008R2 ,2012) Asp.net application throwing error:

var obj_1 = typeof(HttpRuntime).GetProperty("CacheInternal", BindingFlags.NonPublic | BindingFlags.Static); 

CacheInternal is coming null, dont know why ?

following solution is not working :( Solution