I tried to unpack a .zip file using XFCE's file roller (aka "Archive Manager"), but got the error message:
So I tried it in the shell."An error occurred while extracting files"
There I got a slightly more informative error message:
OS is Xubuntu 14.04."need PK compat. v5.1 (can do v4.6)"
[SOLUTION]
Will see what I can do.