The remote host is missing an update to ecryptfs-utils announced via advisory USN-783-1.
The problem can be corrected by upgrading your system to the following package versions: Ubuntu 9.04: ecryptfs-utils 73-0ubuntu6.1 In general, a standard system upgrade is sufficient to effect the necessary changes. https://secure1.securityspace.com/smysecure/catid.html?in=USN-783-1
Chris Jones discovered that the eCryptfs support utilities would report the mount passphrase into installation logs when an eCryptfs home directory was selected during Ubuntu installation. The logs are only readable by the root user, but this still left the mount passphrase unencrypted on disk, potentially leading to a loss of privacy.