Unable to cast EntityEntry current value

I have the same method in EF 6 and working just fine, but using EF core v1.1.1 is with method throwing an exception like this. Please take a look.

     public virtual T Update(T obj)
    {
        try
        {
            if (null == obj) throw new ArgumentNullException(nameof(obj));

            _context.Set<T>().Attach(obj);

            var entry = _context.Entry(obj);

            foreach (var property in entry.OriginalValues.Properties)
            {
                var current = entry.CurrentValues.GetValue<object>(property.Name); // <-- error occurring this line. If i set the generic type to specific like int,string etc the code work for the specific type only but if i set to object won't work.
                entry.Property(property.Name).IsModified = current != null;
            }

            _context.SaveChanges();

            //Detached the current context to get changes value
            _context.Entry(obj).State = EntityState.Detached;

            return obj;
        }
        catch (Exception ex)
        {

            Console.Write(ex);
            throw;
        }
    }