I cant add or upload image in item. When I try to upload an image I get that error in screnshoot. I tried changing /media/k2 directory to 777 permissions (including /media/k2/items/cache and /src ) with no results. Even with the error I can see my picture is uploaded with ftp in /media/k2/items/src .Also when I click the "Browse server" button I can see the popup window with copyright at the bottom and "about this softvare" at the top but there are no pictures. Upload and adding images works with default joomla.

The folder permission should be 755. In general you should avoid 777.

Make sure that the folder have the correct permission and they belong to the correct user/group.

Finally make sure the PHP memory limits are not too low and the server can process the image resizing functions.

You can increase the max execution times and memory limits from K2's params.