Comment 3 for bug 1297044

The underlying reason for this error is rooted in the move to the /run filesystem in 2011. Unless /etc/init/mounted-dev.conf is run a symlink from /dev/shm to /run/shm is not created.[1]

/usr/bin/ecryptfs-mount-private itself executes /sbin/mount.ecryptfs_private, which in turn is built to exepect /dev/shm to exist.[2]

[1]: http://metadata.ftp-master.debian.org/changelogs/main/m/mountall/oldstable_changelog
[2]: http://bazaar.launchpad.net/~ecryptfs/ecryptfs/trunk/view/head:/src/utils/mount.ecryptfs_private.c#L55