The eval code method was removed. All existing code methods using it will change to create_function usage. A re-save isn't needed, but your code may need to be fixed depending on what you were doing. Eval was modifying variables outside its scope as it's inline execution. This was causing things like $this, $trigger, $user, etc.. to be modified and broke CB Auto Actions as it was modifying those variables of the action not just of your own code. This isn't an issue with create_function.