最近我终于决定升级到 ubuntu 18.04。完成更新后，登录后无法获得任何图形界面。到目前为止，我只看到背景，没有其他内容。经过多次尝试，我已从 lightdm 转移到 gdm3，但仍然没有成功。
我创建了一个新用户并且它可以有一个工作的 GUI，但是由于某些我不知道的原因，它是 kde 而不是 gnome。
更有趣的是，我在文本界面启动后得到了一个 gnome 桌面，如下所示/usr/lib/gnome-session/run-systemd-session gnome-session-flashback.target
这就是 gdm3 journalctl 日志中报告的内容（见下文）。我觉得很奇怪，如果手动启动，gnome 可以工作，但如果使用 gdm3（以及 lightdm）启动，gnome 则不行。
经过两天的摸索，我迷失了方向。所以我请求你的帮助！！如果我可以提供更多详细信息，请告诉我。
dic 18 01:00:14 oslo-Inspiron-N5110 gdm3[5235]: GdmManager: client disconnected
dic 18 01:00:14 oslo-Inspiron-N5110 gdm3[5235]: GdmSession: external connection closed
dic 18 01:00:14 oslo-Inspiron-N5110 gdm3[5235]: GdmDisplay: Got timed login details for display: 0
dic 18 01:00:14 oslo-Inspiron-N5110 gdm3[5235]: GdmManager: client connected
dic 18 01:00:14 oslo-Inspiron-N5110 gdm3[5235]: GdmSession: Handling new connection from outside
dic 18 01:00:14 oslo-Inspiron-N5110 gdm3[5235]: GdmDBusServer: new connection 0x55dbcf07ab80
dic 18 01:00:14 oslo-Inspiron-N5110 gdm3[5235]: GdmManager: trying to open new session
dic 18 00:58:34 oslo-Inspiron-N5110 gdm3[5235]: GdmLocalDisplayFactory: display status changed: 2
dic 18 00:58:34 oslo-Inspiron-N5110 gdm3[5235]: Adding or updating utmp record for login
dic 18 00:58:34 oslo-Inspiron-N5110 gdm3[5235]: Writing wtmp session record to /var/log/wtmp
dic 18 00:58:34 oslo-Inspiron-N5110 gdm3[5235]: using ut_line :3
dic 18 00:58:34 oslo-Inspiron-N5110 gdm3[5235]: using ut_host :3
dic 18 00:58:34 oslo-Inspiron-N5110 gdm3[5235]: using ut_pid 5476
dic 18 00:58:34 oslo-Inspiron-N5110 gdm3[5235]: using ut_tv time 1545091114
dic 18 00:58:34 oslo-Inspiron-N5110 gdm3[5235]: using ut_type USER_PROCESS
dic 18 00:58:34 oslo-Inspiron-N5110 gdm3[5235]: Writing login record
dic 18 00:58:34 oslo-Inspiron-N5110 gdm3[5235]: using ut_user oslo
dic 18 00:58:34 oslo-Inspiron-N5110 gdm3[5235]: GdmSession: Setting display device: tty5
dic 18 00:58:34 oslo-Inspiron-N5110 gdm3[5235]: GdmManager: trying to register new display
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmManager: session started 5476
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmSession: Emitting 'session-started' signal with pid '5476'
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: GdmSession worker: watching pid 5476
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: GdmSessionWorker: state SESSION_STARTED
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: GdmSessionWorker: session opened creating reply...
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: Process exit status: 0
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: Gdm: script environment: PATH=/usr/local/bin:/usr/bin:/bin:/usr/games
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: Gdm: script environment: SHELL=/bin/bash
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: Gdm: script environment: USER=oslo
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: Gdm: script environment: PWD=/home/oslo
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: Gdm: script environment: USERNAME=oslo
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: Gdm: script environment: LOGNAME=oslo
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: Gdm: script environment: RUNNING_UNDER_GDM=true
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: Gdm: script environment: GROUP=oslo
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: Gdm: script environment: HOME=/home/oslo
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: Running process: /etc/gdm3/PreSession/Default
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: Trying script /etc/gdm3/PreSession/Default
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: script /etc/gdm3/PreSession not found; skipping
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: Trying script /etc/gdm3/PreSession
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: no script found
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: script /etc/gdm3/PostLogin/Default not found; skipping
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: Trying script /etc/gdm3/PostLogin/Default
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: script /etc/gdm3/PostLogin not found; skipping
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: Trying script /etc/gdm3/PostLogin
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: GdmSessionWorker: VT mode did not need to be fixed
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: GdmSessionWorker: first setting graphics mode to prevent flicker
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: GdmSessionWorker: jumping to VT 5
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: GdmSessionWorker: opening user session with program '/usr/lib/gdm3/gdm-x-session'
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: GdmSessionWorker: attempting to change state to SESSION_STARTED
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: GdmSessionWorker: start program: /usr/lib/gdm3/gdm-x-session --run-script "/usr/lib/gnome-session/run-systemd-session gnome-session-flashback.target"
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: GdmSessionWorker: Set PAM environment variable: 'XDG_CURRENT_DESKTOP=GNOME-Flashback:GNOME'
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: GdmSessionWorker: Set PAM environment variable: 'DESKTOP_SESSION=gnome-flashback-compiz'
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: GdmSessionWorker: Set PAM environment variable: 'XDG_SESSION_DESKTOP=gnome-flashback-compiz'
dic 18 00:58:33 oslo-Inspiron-N5110 gdm-password][5458]: GdmSessionWorker: Set PAM environment variable: 'GDMSESSION=gnome-flashback-compiz'
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmSession: type (null), program? no, seat seat0
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmSession: getting desktop names for file 'gnome-flashback-compiz.desktop'
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmSession: checking if file 'gnome-flashback-compiz.desktop' is wayland session: no
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmSession: getting session command for file 'gnome-flashback-compiz.desktop'
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmSession: type (null), program? no, seat seat0
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmSession: Stopping all conversations except for gdm-password
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmDisplayStore: Adding display /org/gnome/DisplayManager/Displays/94402559583056 to store
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmDisplay: session id: 14
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmDisplay: seat id: seat0
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmDisplay: session class: user
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmDisplay: local: yes
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmDisplay: allow timed login: yes
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmDisplay: initial: no
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmDisplay: session class: greeter
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmDisplay: seat id: (null)
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmDisplay: id: (null)
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmSession: Setting display device: (null)
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmSession: D-Bus server for greeters listening on unix:abstract=/tmp/dbus-rTKiidoM
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmSession: Creating D-Bus server for greeters and such
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmSession: D-Bus server for workers listening on unix:abstract=/tmp/dbus-Leh2ElVX
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmSession: Creating D-Bus server for worker for session
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmManager: session has its display server, reusing our server for another login screen
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmSession: type (null), program? no, seat seat0
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmManager: migrated: 0
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmManager: start or jump to session
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmManager: Will start session when ready
dic 18 00:58:33 oslo-Inspiron-N5110 gdm3[5235]: GdmSession: Emitting 'session-opened' signal