Error using automated upgrade

I’m trying to upgrade to 0.6.3 from I believe 0.5.5 (view source on a page shows ). After about 30 seconds I got the following error

Fatal error: Call to undefined method Piwik::getloginpluginname() in /HOMEDIR/core/View.php on line 132

I received a similar error trying to upgrade from 0.6.2 so I just restored from a back up. How can I install the upgrade?