今天我无法登录GUI，但我可以使用控制台（++ Ctrl）以用户或root身份登录，并且可以通过ssh登录。AltF1
在 Natty 下，升级之前，我已将 Ubuntu 设置为自动以用户身份登录。周五，自动登录在 12.04 上工作正常。今天我第一次看到登录屏幕。系统没有提示我输入用户 ID，只是要求我输入密码。
$ sudo cat /var/log/lightdm/lightdm.log
[+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.00s] DEBUG: Starting Light Display Manager 1.2.1, UID=0 PID=1421
[+0.00s] DEBUG: Loaded configuration from /etc/lightdm/lightdm.conf
[+0.00s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.00s] DEBUG: Registered seat module xlocal
[+0.00s] DEBUG: Registered seat module xremote
[+0.00s] DEBUG: Adding default seat
[+0.00s] DEBUG: Starting seat
[+0.00s] DEBUG: Starting new display for automatic login as user mslinn
[+0.00s] DEBUG: Starting local X display
[+0.02s] DEBUG: X server :0 will replace Plymouth
[+0.04s] DEBUG: Using VT 7
[+0.04s] DEBUG: Activating VT 7
[+0.04s] DEBUG: Logging to /var/log/lightdm/x-0.log
[+0.04s] DEBUG: Writing X server authority to /var/run/lightdm/root/:0
[+0.04s] DEBUG: Launching X Server
[+0.04s] DEBUG: Launching process 1452: /usr/bin/X :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch -background none
[+0.04s] DEBUG: Waiting for ready signal from X server :0
[+0.04s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
[+0.04s] DEBUG: Registering seat with bus path /org/freedesktop/DisplayManager/Seat0
[+0.41s] DEBUG: Got signal 10 from process 1452
[+0.41s] DEBUG: Got signal from X server :0
[+0.41s] DEBUG: Stopping Plymouth, X server is ready
[+0.43s] DEBUG: Connecting to XServer :0
[+0.43s] DEBUG: Automatically logging in user mslinn
[+0.43s] DEBUG: Started session 1524 with service 'lightdm-autologin', username 'mslinn'
[+0.49s] DEBUG: Session 1524 authentication complete with return value 0: Success
[+0.49s] DEBUG: Autologin user mslinn authorized
[+0.49s] DEBUG: Autologin using session xterm
[+0.50s] DEBUG: Dropping privileges to uid 1000
[+0.50s] DEBUG: Restoring privileges
[+0.51s] DEBUG: Dropping privileges to uid 1000
[+0.51s] DEBUG: Writing /home/mslinn/.dmrc
[+0.53s] DEBUG: Restoring privileges
[+0.57s] DEBUG: Starting session xterm as user mslinn
[+0.57s] DEBUG: Session 1524 running command /usr/sbin/lightdm-session xterm
[+0.65s] DEBUG: New display ready, switching to it
[+0.65s] DEBUG: Activating VT 7
[+0.66s] DEBUG: Registering session with bus path /org/freedesktop/DisplayManager/Session0
[+0.89s] DEBUG: Session 1524 exited with return value 0
[+0.97s] DEBUG: User session quit
[+0.97s] DEBUG: Stopping display
[+0.97s] DEBUG: Sending signal 15 to process 1452
[+2.20s] DEBUG: Process 1452 exited with return value 0
[+2.20s] DEBUG: X server stopped
[+2.20s] DEBUG: Removing X server authority /var/run/lightdm/root/:0
[+2.20s] DEBUG: Releasing VT 7
[+2.20s] DEBUG: Display server stopped
[+2.20s] DEBUG: Display stopped
[+2.20s] DEBUG: Active display stopped, switching to greeter
[+2.20s] DEBUG: Switching to greeter
[+2.20s] DEBUG: Starting new display for greeter
[+2.20s] DEBUG: Starting local X display
[+2.20s] DEBUG: Using VT 7
[+2.20s] DEBUG: Logging to /var/log/lightdm/x-0.log
[+2.21s] DEBUG: Writing X server authority to /var/run/lightdm/root/:0
[+2.21s] DEBUG: Launching X Server
[+2.21s] DEBUG: Launching process 1758: /usr/bin/X :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
[+2.21s] DEBUG: Waiting for ready signal from X server :0
[+2.43s] DEBUG: Got signal 10 from process 1758
[+2.43s] DEBUG: Got signal from X server :0
[+2.43s] DEBUG: Connecting to XServer :0
[+2.43s] DEBUG: Starting greeter
[+2.43s] DEBUG: Started session 1766 with service 'lightdm', username 'lightdm'
[+2.61s] DEBUG: Session 1766 authentication complete with return value 0: Success
[+2.61s] DEBUG: Greeter authorized
[+2.61s] DEBUG: Logging to /var/log/lightdm/x-0-greeter.log
[+2.66s] DEBUG: Session 1766 running command /usr/lib/lightdm/lightdm-greeter-session /usr/sbin/unity-greeter
[+3.12s] DEBUG: Greeter connected version=1.2.1
[+3.12s] DEBUG: Greeter connected, display is ready
[+3.12s] DEBUG: New display ready, switching to it
[+3.12s] DEBUG: Activating VT 7
[+3.12s] DEBUG: Stopping greeter display being switched from
[+3.91s] DEBUG: Greeter start authentication for mslinn
[+3.91s] DEBUG: Started session 2219 with service 'lightdm', username 'mslinn'
[+3.99s] DEBUG: Session 2219 got 1 message(s) from PAM
[+3.99s] DEBUG: Prompt greeter with 1 message(s)
我尝试卸载并重新安装lightdm，但没有帮助。
我有 3 个虚拟化 Ubuntu 系统；其中两个有这个问题。我该怎么办？
答案1
我解决这个问题的方法是删除并重新安装 lightdm 和 ubuntu-desktop。问题立即解决。您可能必须确保删除缓存的包并确保它从存储库下载新版本。