Can I save model inside hook on_state_entry?

[deemytch]

class Meeting < ActiveRecord::Base
[skip]
def on_uploading_entry(ns, ev, *args)
  self.stopped_at = Time.now
  self.duration = new_duration
  set_some_other_fields
  ...
  self.save!
end
[skip]
end

causes

#<ActiveModel::Errors:0x00000001c5c4d8 @base=#<Meeting id: 580, [skip] >, @messages={:base=>["Cannot save myself in :uploading state."]}>