Thanks for this update. I close the bug now. It looks like either inodes ran out or a full filesystem or fs corruption. Most likely nothing to do with g-a-i directly :)
** Changed in: gnome-app-install (Ubuntu) Status: Needs Info => Fix Released -- app-install-data broken and unable to update https://launchpad.net/bugs/66651 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs