K2 FrontEnd Editing - Error 500

Hello,

I have this problem when user (member of the SiteOwner group of K2) try to Save the edited article from the FrontEnd Popup window:

Oops, you've encountered an error 500

It appears the page you were looking for doesn't exist. Sorry about that.

Can you please tell me where to search to fix it?

btw. I have the K2 transalation to Slovak Language if this is any help for you.

and link to the web: www.pizzeria-luky.sk

Thx

Rudo

Dear gavickpro developers,

is there any chance that someone will reply? I really need to at least point out what to check to solve this issue. Can you please help me with it? I put a trust in you and don't want to loose the overall good feeling!

Thank you in advance
Rudo