我的电脑最近意外关机，原因不明。last命令显示系统崩溃，但我无法在系统日志中找到任何原因：
最后输出：
reboot system boot 4.15.0-46-generi Thu Mar 28 10:02 - 10:22 (00:20)
username tty2 tty2 Thu Mar 28 08:39 - crash (01:22)
reboot system boot 4.15.0-46-generi Thu Mar 28 08:39 - 10:22 (01:42)
系统日志：
Mar 28 09:53:11 U-C-001 gdm-session-worker[1589]: modprobe: ERROR: could not insert 'nvidia': Required key not available
Mar 28 09:53:11 U-C-001 kernel: [ 4453.744318] PKCS#7 signature not signed with a trusted key
Mar 28 09:53:14 U-C-001 gnome-software[2757]: no app for changed [email protected]
Mar 28 09:53:14 U-C-001 gnome-software[2757]: no app for changed [email protected]
Mar 28 09:53:14 U-C-001 gnome-shell[1675]: [AppIndicatorSupport-DEBUG] Registering StatusNotifierItem :1.75/org/ayatana/NotificationItem/software_update_available
Mar 28 09:53:16 U-C-001 firefox_firefox.desktop[6462]: /snap/firefox/198/bin/desktop-launch: line 174: /home/username/snap/firefox/common/.config/user-dirs.dirs: No such file or directory
Mar 28 09:53:16 U-C-001 firefox_firefox.desktop[6462]: cp: cannot create regular file '/home/username/snap/firefox/common/.config/': Not a directory
Mar 28 09:53:16 U-C-001 firefox_firefox.desktop[6462]: /snap/firefox/198/bin/desktop-launch: line 177: /home/username/snap/firefox/common/.config/user-dirs.dirs.md5sum: No such file or directory
Mar 28 09:53:16 U-C-001 firefox_firefox.desktop[6462]: /snap/firefox/198/bin/desktop-launch: line 177: /home/username/snap/firefox/common/.config/user-dirs.locale.md5sum: No such file or directory
Mar 28 09:53:16 U-C-001 firefox_firefox.desktop[6462]: Gtk-Message: Failed to load module "canberra-gtk-module"
Mar 28 09:53:16 U-C-001 kernel: [ 4458.808586] audit: type=1400 audit(1553763196.420:60): apparmor="DENIED" operation="open" profile="snap.firefox.firefox" name="/proc/6462/net/arp" pid=6462 comm=4C696E6B204D6F6E69746F72 requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
Mar 28 09:53:16 U-C-001 firefox_firefox.desktop[6462]: Gtk-Message: Failed to load module "canberra-gtk-module"
Mar 28 09:53:16 U-C-001 firefox_firefox.desktop[6462]: (firefox:6462): Gtk-CRITICAL **: gtk_widget_get_style_context: assertion 'GTK_IS_WIDGET (widget)' failed
Mar 28 09:53:16 U-C-001 firefox_firefox.desktop[6462]: (firefox:6462): Gtk-CRITICAL **: gtk_style_context_get_state: assertion 'GTK_IS_STYLE_CONTEXT (context)' failed
Mar 28 09:53:16 U-C-001 firefox_firefox.desktop[6462]: (firefox:6462): Gtk-CRITICAL **: gtk_style_context_set_state: assertion 'GTK_IS_STYLE_CONTEXT (context)' failed
Mar 28 09:53:16 U-C-001 firefox_firefox.desktop[6462]: (firefox:6462): Gtk-CRITICAL **: gtk_render_background: assertion 'GTK_IS_STYLE_CONTEXT (context)' failed
Mar 28 09:53:16 U-C-001 firefox_firefox.desktop[6462]: (firefox:6462): Gtk-CRITICAL **: gtk_render_frame: assertion 'GTK_IS_STYLE_CONTEXT (context)' failed
Mar 28 09:53:16 U-C-001 firefox_firefox.desktop[6462]: Gtk-Message: Failed to load module "canberra-gtk-module"
Mar 28 09:53:16 U-C-001 firefox_firefox.desktop[6462]: Gtk-Message: Failed to load module "canberra-gtk-module"
Mar 28 09:53:17 U-C-001 gnome-shell[1675]: JS ERROR: Exception in callback for signal: activate: Error: Error invoking IBus.set_global_engine_async: Expected function for callback argument callback, got undefined#012setEngine@resource:///org/gnome/shell/misc/ibusManager.js:207:9#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22#012activateInputSource@resource:///org/gnome/shell/ui/status/keyboard.js:490:13#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22#012_emit@resource:///org/gnome/gjs/modules/signals.js:128:27#012activate@resource:///org/gnome/shell/ui/status/keyboard.js:65:9#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22#012_inputSourcesChanged@resource:///org/gnome/shell/ui/status/keyboard.js:620:13#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22#012reload@resource:///org/gnome/shell/ui/status/keyboard.js:369:9#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22#012_ibusSetContentType@resource:///org/gnome/shell/ui/status/keyboard.js:691:9#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22#012_emit@resource:///org/gnome/gjs/modules/signals.js:128:27#012_setContentType@resource:///org/gnome/shell/misc/ibusManager.js:183:9#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22
Mar 28 09:53:17 U-C-001 firefox_firefox.desktop[6462]: Gtk-Message: Failed to load module "canberra-gtk-module"
Mar 28 09:53:18 U-C-001 firefox_firefox.desktop[6462]: message repeated 3 times: [ Gtk-Message: Failed to load module "canberra-gtk-module"]
Mar 28 09:53:29 U-C-001 gdm-session-worker[1589]: modprobe: ERROR: could not insert 'nvidia': Required key not available
Mar 28 09:53:29 U-C-001 kernel: [ 4471.952558] PKCS#7 signature not signed with a trusted key
Mar 28 09:53:32 U-C-001 firefox_firefox.desktop[6462]: Gtk-Message: Failed to load module "canberra-gtk-module"
Mar 28 09:53:32 U-C-001 firefox_firefox.desktop[6462]: Gtk-Message: Failed to load module "canberra-gtk-module"
Mar 28 09:54:45 U-C-001 org.gnome.Shell.desktop[1675]: Window manager warning: last_user_time (4548485) is greater than comparison timestamp (4548484). This most likely represents a buggy client sending inaccurate timestamps in messages such as _NET_ACTIVE_WINDOW. Trying to work around...
Mar 28 09:54:45 U-C-001 org.gnome.Shell.desktop[1675]: Window manager warning: 0x1c00010 ([firefox website name]) appears to be one of the offending windows with a timestamp of 4548485. Working around...
Mar 28 09:54:46 U-C-001 org.gnome.Shell.desktop[1675]: Window manager warning: last_user_time (4548515) is greater than comparison timestamp (4548514). This most likely represents a buggy client sending inaccurate timestamps in messages such as _NET_ACTIVE_WINDOW. Trying to work around...
Mar 28 09:54:46 U-C-001 org.gnome.Shell.desktop[1675]: Window manager warning: 0x1c00010 ([firefox website name]) appears to be one of the offending windows with a timestamp of 4548515. Working around...
Mar 28 09:54:49 U-C-001 org.gnome.Shell.desktop[1675]: Window manager warning: last_user_time (4551614) is greater than comparison timestamp (4551613). This most likely represents a buggy client sending inaccurate timestamps in messages such as _NET_ACTIVE_WINDOW. Trying to work around...
Mar 28 09:54:49 U-C-001 org.gnome.Shell.desktop[1675]: Window manager warning: 0x1c00010 ([firefox website name]) appears to be one of the offending windows with a timestamp of 4551614. Working around...
Mar 28 09:54:52 U-C-001 org.gnome.Shell.desktop[1675]: Window manager warning: last_user_time (4555028) is greater than comparison timestamp (4555027). This most likely represents a buggy client sending inaccurate timestamps in messages such as _NET_ACTIVE_WINDOW. Trying to work around...
Mar 28 09:54:52 U-C-001 org.gnome.Shell.desktop[1675]: Window manager warning: 0x1c00010 ([firefox website name]) appears to be one of the offending windows with a timestamp of 4555028. Working around...
Mar 28 09:59:39 U-C-001 kernel: [ 4841.893118] [UFW BLOCK] IN=wlp3s0 OUT= MAC=[MAC] SRC=[router internal IP] DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0xC0 TTL=1 ID=15777 PROTO=2
Mar 28 10:02:33 U-C-001 systemd[1]: Started udev Coldplug all Devices.
Mar 28 10:02:33 U-C-001 kernel: [ 0.000000] microcode: microcode updated early to revision 0x8e, date = 2018-03-24
Mar 28 10:02:33 U-C-001 kernel: [ 0.000000] Linux version 4.15.0-46-generic (buildd@lgw01-amd64-038) (gcc version 7.3.0 (Ubuntu 7.3.0-16ubuntu3)) #49-Ubuntu SMP Wed Feb 6 09:33:07 UTC 2019 (Ubuntu 4.15.0-46.49-generic 4.15.18)
虽然系统日志中有几个错误，但它们都发生在关机前几分钟，似乎与关机无关。有没有办法进一步调查这个问题？你知道是什么原因导致关机的吗？我正在运行 Ubuntu 18.04.02。
编辑： 从注释中移出的附加命令输出
ls -R /lib/modules/uname -r/kernel/|grep noveau
nouveau
/lib/modules/4.15.0-46-generic/kernel/drivers/gpu/drm/nouveau:
nouveau.ko
ls -R /lib/modules/uname -r/kernel/| grep nvidia
nvidia
/lib/modules/4.15.0-46-generic/kernel/drivers/net/ethernet/nvidia:
nvidia
/lib/modules/4.15.0-46-generic/kernel/drivers/video/fbdev/nvidia:
nvidiafb.ko
编辑2： 附加命令输出
modprobe nvidia
modprobe: ERROR: could not insert 'nvidia': Required key not available
请参阅lspci-k | grep -A 2 -E “(VGA|3D)”
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 620 (rev 02)
Subsystem: Acer Incorporated [ALI] HD Graphics 620
Kernel driver in use: i915
--
01:00.0 3D controller: NVIDIA Corporation Device 179c (rev a2)
Subsystem: Acer Incorporated [ALI] Device 1094
Kernel modules: nvidiafb, nouveau, nvidia_drm, nvidia
编辑3：不禁用 SecureBoot 的附加命令输出
mokutil --sb-state
SecureBoot enabled
ls /sys/固件/efi
config_table esrt fw_vendor runtime-map vars
efivars fw_platform_size runtime systab
sudo lshw -c 视频 | grep'配置'
configuration: driver=i915 latency=0
configuration: latency=0