Originally Posted by kovidgoyal
The message could not find mount helper means your installation is not complete.
Try re-installing or set up Ubuntu to automount the sony reader, in which case the mount helper wont be needed.
Ubuntu does auto-mount the reader. It even opens up the internal storage in a Nautilus window, where I can add/remove files. But the calibre mount helper message still would come up when using Ubuntu's calibre package.
Only way to fix was to uninstall their package and use the instructions.