Hello,
You can check the full list of changes here. If you would like us to take a look at the code please paste it here. May I ask why you're not using Kentico controls and methods?
You can set the context like this:
CMSContext.AuthenticateUser("UserName", true, true);
OR
CMSContext.CurrentUser = new CurrentUserInfo(ui, true);
Please let me know if you have any questions or additional information.
Regards,
Sandro