i get this on my front site:
Invalid backend model specified: catalog/category_attribute_backend_image
Hai, you can read the solution in here :
http://magento.stackexchange.com/questions/98220/security-patch-supee-7405-possible-problems
including discusses:
List of affected files
It can be found on this page here: http://magento.stackexchange.com/a/98232/2380 (credits @MagenX)