ecryptfs "mount: No such file or directory" after upgrade to 18.04

[Kevin Otte]

Attempted to mount my ecryptfs Private folder for the first time after upgrading from 16.04 -> 18.04.

$ ecryptfs-mount-private
Enter your wrapping passphrase:
Inserted auth tok with sig [redacted] into the user session keyring
mount: No such file or directory

Workaround:
$ sudo ecryptfs-mount-private
...
fopen: No such file or directory
$ ecryptfs-mount-private

After executing the workaround:

$ ecryptfs-umount-private
Sessions still open, not unmounting

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ecryptfs-utils 111-0ubuntu5
ProcVersionSignature: Ubuntu 4.15.0-32.35-generic 4.15.18
Uname: Linux 4.15.0-32-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
CurrentDesktop: XFCE
Date: Wed Aug 22 14:37:10 2018
EcryptfsInUse: Yes
InstallationDate: Installed on 2011-12-09 (2448 days ago)
InstallationMedia: Xubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
SourcePackage: ecryptfs-utils
UpgradeStatus: Upgraded to bionic on 2018-08-11 (10 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.