yusukenishihara wrote: Thank you for your advise. I understood CB upgrade is done by just installing new version. Is CB1.8 worked in PHP 5.1.x environment?
Yes, on Joomla 1.5 all you need to do in order to upgrade from CB 1.7 to CB 1.8 is to install CB 1.8 over existing environment.
(also documented in CB 1.8 installation document and upgrade text files)