Im upgrade today my k2 component to lastest version 2.5.4 and have problem I cant edit or add new item neither frontend or backend I always got error 500

500 - An error has occurred.

Unable to load format class

Please help me its very important

Im use joomla 1.7 and gavick template World News II

I cant bealive is so used component have so terrible support Im menu years avoid to install this and now with new version of site i decide to use K@ and regret Im make business to self and now must put site offline and transfer all articles to joomla format.I never have some problem with joomla ho not resolved by developers. I see some other peoples have same problem on this forum and many of them stay without any answer that very unprofessional

goodbay K2 and never again