Same on 16.04.3 after updating Unity to latest proposed packages. Also on 17.10 with installed unity-session.
For me, this issue appears after switching to another user. Steps to reproduce (must be more than one local users on system, eg. "bob", "alice"): 1. Login under bob. 2. Via upper-right menu switch to "alice". 3. On greeter screen setect "alice", login under alice. 4. Logout, return to greeter screen. 5. Select bob (already logged in). Enter password. 6. Lock screen. Issue appeared. Issue appeared on every screen lock. Messages in syslog: Jan 6 17:15:33 eugene-Lenovo-Flex-2-14 systemd[1411]: Stopped Backing Service for the Unity Panel in Lockscreen mode. Jan 6 17:15:42 eugene-Lenovo-Flex-2-14 compiz[1877]: WARN 2018-01-06 17:15:42 unity.lockscreen UserPromptView.cpp:500 Failed to start the authentication process. Retrying for 1 time. Jan 6 17:15:42 eugene-Lenovo-Flex-2-14 compiz[1877]: WARN 2018-01-06 17:15:42 unity.lockscreen UserPromptView.cpp:500 Failed to start the authentication process. Retrying for 2 time. Jan 6 17:15:42 eugene-Lenovo-Flex-2-14 systemd[1411]: Starting Backing Service for the Unity Panel in Lockscreen mode... Jan 6 17:15:42 eugene-Lenovo-Flex-2-14 compiz[1877]: WARN 2018-01-06 17:15:42 unity.glib.dbus.proxy GLibDBusProxy.cpp:487 Calling method "EmitEvent" on object path: "/com/ubuntu/Upstart" failed: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name com.canonical.Unity.Test.Upstart was not provided by any .service files Jan 6 17:15:42 eugene-Lenovo-Flex-2-14 systemd-prestart-check[3804]: grep: /usr/share/gnome-session/sessions/ubuntu.session: Нет такого файла или каталога Jan 6 17:15:42 eugene-Lenovo-Flex-2-14 systemd[1411]: Started Backing Service for the Unity Panel in Lockscreen mode. Jan 6 17:15:42 eugene-Lenovo-Flex-2-14 systemd[1411]: Reached target A target that, when running, represents the screen being locked. Jan 6 17:15:42 eugene-Lenovo-Flex-2-14 compiz[1877]: WARN 2018-01-06 17:15:42 unity.lockscreen UserPromptView.cpp:500 Failed to start the authentication process. Retrying for 3 time. Jan 6 17:15:42 eugene-Lenovo-Flex-2-14 compiz[1877]: WARN 2018-01-06 17:15:42 unity.lockscreen UserPromptView.cpp:500 Failed to start the authentication process. Retrying for 4 time. Jan 6 17:15:42 eugene-Lenovo-Flex-2-14 compiz[1877]: WARN 2018-01-06 17:15:42 unity.lockscreen UserPromptView.cpp:500 Failed to start the authentication process. Retrying for 5 time. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to lightdm in Ubuntu. https://bugs.launchpad.net/bugs/1733557 Title: Login screen showing Authentication Failed Switch to greeter... Status in lightdm package in Ubuntu: Confirmed Bug description: When I lock my machine, the login screen shows my current user with the message: "Authentication Failed" ..and in the position when the password normally exists, the option "Switch to greeter..." ProblemType: Bug DistroRelease: Ubuntu 17.10 Package: gnome-control-center 1:3.26.1-0ubuntu5 ProcVersionSignature: Ubuntu 4.13.0-16.19-generic 4.13.4 Uname: Linux 4.13.0-16-generic x86_64 ApportVersion: 2.20.7-0ubuntu3.5 Architecture: amd64 CurrentDesktop: Unity:Unity7:ubuntu Date: Tue Nov 21 10:28:47 2017 InstallationDate: Installed on 2017-04-17 (217 days ago) InstallationMedia: Ubuntu 16.10 "Yakkety Yak" - Release amd64 (20161012.2) ProcEnviron: LANGUAGE=en_GB:en PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_GB.UTF-8 SHELL=/bin/bash SourcePackage: gnome-control-center UpgradeStatus: Upgraded to artful on 2017-10-23 (29 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lightdm/+bug/1733557/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
