Hi!
In 3.2.7 this code was possible if 'auto_models_for_select' is nil : <%= select_tag :model, auto_models_for_select, :include_blank => true, :disabled => auto_models_for_select.nil? %>
In 3.2.8 this should be : <%= select_tag :model, auto_models_for_select || '', :include_blank => true, :disabled => auto_models_for_select.nil? %>
If second parameter is nil it raise an exception.
Please, return back that it was possible to transfer nil of second parameter - options.