Update to Joomla 3 from 2.5 isn't going well - Joomla! Forum - community, help and support

forgive me if ramble somewhat; think information important.

i'm super excited see joomla 3 me on of sites manage. first , foremost company's own site. site joomla 2.5.8 , uses k2. because bought template third party uses k2 , other plugins. (i wasn't particularly excited add complexity own site wanted online gulped , went forward.)

so, after backup decided best approach unzip (via command line) file "joomla_3.0.2-stable-update_package.zip" on top of installation. presume proper approach, unable find documentation anywhere explaining best upgrade method.

this naturally broke site.

after restoring site backup, knew not turnkey operation. created test fork of site , tried again. time found had (and did) update k2 , rokmenu latest versions. noted mootools fixes framework , made those. after doing of that, site sorta works. homepage looks perfect interior pages broken. also, administrator pages seem work funky. (i'm including snapshot.)

the item concerns me interior pages of site broken. i've looked @ server logs , find each page load aborts kind of error:

[wed dec 26 17:27:13 2012] [error] [client xxx.xxx.xxx.xxx] php fatal error: call undefined method jparameter::loadini() in /var/www/vhosts/testing.mysite.com/httpdocs/libraries/joomla/html/parameter.php on line 76, referer: http://testing.mysite.com/index.php/

my thoughts perhaps joomla discovering old code might removed better installation method(?) i'm guessing here, i'm on head organization of software. ideas go here?

you changed system? mysite.com isn't working joomla.

please use in in further questions example.org instead of other domains