Failed 4.0 upgrade
 

Hi to all
I've tried to upgrade (LIVE) forum from 3.8.4 to 4.0 got me into all sorts of database errors;
basically my forum is dead!
I restored an older dbase backup copy then reinstalled/uploaded back all 3.8.4 files;
when I run the upgrade I get this error
Fatal error: Call to undefined method vBulletinHook::init() in /home/public_html/vb/install/init.php on line 21
Can someone help ?

regards