Secondary monitor not connecting in 18.04 LTS

Found a workaround:

        xrandr --addmode HDMI-1-2 1920x1080
        xrandr --output HDMI-1-2 --mode 1920x1080

This sequence of commands enables clone display. However, I still don't see anywhere in Displays/Monitors the secondary display.

Here is the xrandr output (while projector is on):

        HDMI-1-1 disconnected 1920x1080+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
           1920x1080 60.02*

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

Hi guys,

i think, i have the very same problem... but i use AMD video. I'd like to find out if it is the same issue or a different bug. However i cannot use my second monitor...

Any suggests?

Hi,

I think I have the same problem. I have a Latitude 7390 with the WD15 Dock.

I get a connection to the Display Port and VGA but not to the HDMI Port. I have connect my second monitor with HDMI, but it isnt working.

$ xrandr
Screen 0: minimum 320 x 200, current 3840 x 1200, maximum 8192 x 8192
eDP-1 connected (normal left inverted right x axis y axis)
   1920x1080 60.01 + 60.01 59.97 59.96 59.93
   1680x1050 59.95 59.88
   1600x1024 60.17
   1400x1050 59.98
   1600x900 59.99 59.94 59.95 59.82
   1280x1024 60.02
   1440x900 59.89
   1400x900 59.96 59.88
   1280x960 60.00
   1440x810 60.00 59.97
   1368x768 59.88 59.85
   1360x768 59.80 59.96
   1280x800 59.99 59.97 59.81 59.91
   1152x864 60.00
   1280x720 60.00 59.99 59.86 59.74
   1024x768 60.04 60.00
   960x720 60.00
   928x696 60.05
   896x672 60.01
   1024x576 59.95 59.96 59.90 59.82
   960x600 59.93 60.00
   960x540 59.96 59.99 59.63 59.82
   800x600 60.00 60.32 56.25
   840x525 60.01 59.88
   864x486 59.92 59.57
   800x512 60.17
   700x525 59.98
   800x450 59.95 59.82
   640x512 60.02
   720x450 59.89
   700x450 59.96 59.88
   640x480 60.00 59.94
   720x405 59.51 58.99
   684x384 59.88 59.85
   680x384 59.80 59.96
   640x400 59.88 59.98
   576x432 60.06
   640x360 59.86 59.83 59.84 59.32
   512x384 60.00
   512x288 60.00 59.92
   480x270 59.63 59.82
   400x300 60.32 56.34
   432x243 59.92 59.57
   320x240 60.05
   360x202 59.51 59.13
   320x180 59.84 59.32
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected (normal left inverted right x axis y axis)
DP-1-2 connected 1920x1200+0+0 (normal left inverted right x axis y axis) 518mm x 324mm
   1920x1200 59.95*+
   1920x1080 60.00
   1600x1200 60.00
   1680x1050 59.95
   1280x1024 60.02
   1280x960 60.00
   1024x768 60.00
   800x600 60.32
   640x480 59.94
   720x400 70.08
DP-1-1 disconnected (normal left inverted right x axis y axis)
DP-1-3 connected 1920x1200+1920+0 (normal left inverted right x axis y axis) 518mm x 324mm
   1920x1200 59.95*+
   1920x1080 60.00
   1600x1200 60.00
   1680x1050 59.95
   1280x1024 60.02
   1280x960 60.00
   1024x768 60.00
   800x600 60.32
   640x480 59.94
   720x400 70.08

Anyone an idea when to expect a solution?

I have a Dell XPS-15 9570 and I am also affected by this bug.

I am currently running 18.10.

The external monitor does not work with HDMI at all - when I plug it in to the machine, the monitor switches to low power mode.

The same monitor is working fine over HDMI with a Dell M3800 running 16.04

I have a dell inspiron 15 5000 2 in 1, Running ubuntu 18.04, and I am also affected by this bug. I have a DELL U2414M monitor.

Same problem with ASUS S406 (no graphic card, CPU i5-8250U)

The most awkward thing is sometimes it is working, sometimes it's not. I can't figure out why. When not working, even a restart does not re-enable it but xrandr can enable mirroring laptop display.

Any advice?

Also affected with Asus Zenbook UX31E and Ubuntu 18.04.01.

Cannot connect external display via HDMI. Tried to add the hdmi output manually with xrandr as well but I cannot get the external display to be listed anywhere.

xrandr program version 1.5.0
Server reports RandR version 1.5

Looks like the Monitor gets some information about the HDMI cable being connected - but no display signal is received and monitor just goes to sleep.

PS: workaround by Mihai to mirror displays works for me too, to get something on the external display. Same as for Mihai, the display is not listed anywhere.

Here is the xrandr output:

xrandr
Screen 0: minimum 320 x 200, current 1600 x 900, maximum 8192 x 8192
eDP-1 connected primary 1600x900+0+0 (normal left inverted right x axis y axis) 293mm x 164mm
   1600x900 60.00*+ 59.99 59.94 59.95 59.82
   1440x900 59.89
   1400x900 59.96 59.88
   1440x810 60.00 59.97
   1368x768 59.88 59.85
   1360x768 59.80 59.96
   1280x800 59.99 59.97 59.81 59.91
   1152x864 60.00
   1280x720 60.00 59.99 59.86 59.74
   1024x768 60.04 60.00
   960x720 60.00
   928x696 60.05
   896x672 60.01
   1024x576 59.95 59.96 59.90 59.82
   960x600 59.93 60.00
   960x540 59.96 59.99 59.63 59.82
   800x600 60.00 60.32 56.25
   840x525 60.01 59.88
   864x486 59.92 59.57
   800x512 60.17
   700x525 59.98
   800x450 59.95 59.82
   640x512 60.02
   720x450 59.89
   700x450 59.96 59.88
   640x480 60.00 59.94
   720x405 59.51 58.99
   684x384 59.88 59.85
   680x384 59.80 59.96
   640x400 59.88 59.98
   576x432 60.06
   640x360 59.86 59.83 59.84 59.32
   512x384 60.00
   512x288 60.00 59.92
   480x270 59.63 59.82
   400x300 60.32 56.34
   432x243 59.92 59.57
   320x240 60.05
   360x202 59.51 59.13
   320x180 59.84 59.32
VGA-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected 1600x900+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
   1600x900 60.00*
DP-1 disconnected (normal left inverted right x axis y axis)

Same problem, no external monitor via HDMI detected:

Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 16384 x 16384
eDP-1-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 309mm x 173mm
   1920x1080 60.03*+ 60.01 59.97 59.96 59.93 48.03
   1680x1050 59.95 59.88
   1600x1024 60.17
   1400x1050 59.98
   1600x900 59.99 59.94 59.95 59.82
   1280x1024 60.02
   1440x900 59.89
   1400x900 59.96 59.88
   1280x960 60.00
   1440x810 60.00 59.97
   1368x768 59.88 59.85
   1360x768 59.80 59.96
   1280x800 59.99 59.97 59.81 59.91
   1152x864 60.00
   1280x720 60.00 59.99 59.86 59.74
   1024x768 60.04 60.00
   960x720 60.00
   928x696 60.05
   896x672 60.01
   1024x576 59.95 59.96 59.90 59.82
   960x600 59.93 60.00
   960x540 59.96 59.99 59.63 59.82
   800x600 60.00 60.32 56.25
   840x525 60.01 59.88
   864x486 59.92 59.57
   800x512 60.17
   700x525 59.98
   800x450 59.95 59.82
   640x512 60.02
   720x450 59.89
   700x450 59.96 59.88
   640x480 60.00 59.94
   720x405 59.51 58.99
   684x384 59.88 59.85
   680x384 59.80 59.96
   640x400 59.88 59.98
   576x432 60.06
   640x360 59.86 59.83 59.84 59.32
   512x384 60.00
   512x288 60.00 59.92
   480x270 59.63 59.82
   400x300 60.32 56.34
   432x243 59.92 59.57
   320x240 60.05
   360x202 59.51 59.13
   320x180 59.84 59.32
DP-1-1 disconnected (normal left inverted right x axis y axis)
HDMI-1-1 disconnected (normal left inverted right x axis y axis)
DP-1-2 disconnected (normal left inverted right x axis y axis)
HDMI-1-2 disconnected (normal left inverted right x axis y axis)
DP-1-3 disconnected (normal left inverted right x axis y axis)
HDMI-1-3 disconnected (normal left inverted right x axis y axis)

Me to. Would love to be able to use my HDMI monitor:
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192
eDP-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 193mm
   1920x1080 60.06*+ 60.01 59.97 59.96 59.93 40.04
   1680x1050 59.95 59.88
   1600x1024 60.17
   1400x1050 59.98
   1600x900 59.99 59.94 59.95 59.82
   1280x1024 60.02
   1440x900 59.89
   1400x900 59.96 59.88
   1280x960 60.00
   1440x810 60.00 59.97
   1368x768 59.88 59.85
   1360x768 59.80 59.96
   1280x800 59.99 59.97 59.81 59.91
   1152x864 60.00
   1280x720 60.00 59.99 59.86 59.74
   1024x768 60.04 60.00
   960x720 60.00
   928x696 60.05
   896x672 60.01
   1024x576 59.95 59.96 59.90 59.82
   960x600 59.93 60.00
   960x540 59.96 59.99 59.63 59.82
   800x600 60.00 60.32 56.25
   840x525 60.01 59.88
   864x486 59.92 59.57
   800x512 60.17
   700x525 59.98
   800x450 59.95 59.82
   640x512 60.02
   720x450 59.89
   700x450 59.96 59.88
   640x480 60.00 59.94
   720x405 59.51 58.99
   684x384 59.88 59.85
   680x384 59.80 59.96
   640x400 59.88 59.98
   576x432 60.06
   640x360 59.86 59.83 59.84 59.32
   512x384 60.00
   512x288 60.00 59.92
   480x270 59.63 59.82
   400x300 60.32 56.34
   432x243 59.92 59.57
   320x240 60.05
   360x202 59.51 59.13
   320x180 59.84 59.32
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected (normal left inverted right x axis y axis)

I have basically the same problem. I was using 18.04LTS on a HP ZBook15 laptop and also wanted to connect an external monitor by using the HDMI interface. I have 2 graphics cards intel(i915) + NVidia(390drivers), and whatever I chose in prime-select/Nvidia-settings, the external monitor did not work. 'xrandr' always listed the HDMI port as disconnected, which was not true of course. I also tried using different HDMI cables due to stackoverflow suggestions, but this didn't solve the issue. Then, I updated to 18.10, which I still use now, hoping there would be an improvement, but nothing changed. The monitor is still not working, "xrandr" still says that the monitor is disconnected.

Would really be great if this could be solved. Hoping for the best. Thanks!

xrandr output:
Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
eDP1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 340mm x 190mm
   1920x1080 60.00*+ 59.93 40.00
   1680x1050 59.95 59.88
   1600x1024 60.17
   1400x1050 59.98
   1600x900 60.00 59.95 59.82
   1280x1024 60.02
   1440x900 59.89
   1400x900 59.96 59.88
   1280x960 60.00
   1368x768 60.00 59.88 59.85
   1360x768 59.80 59.96
   1280x800 59.81 59.91
   1152x864 60.00
   1280x720 59.86 60.00 59.74
   1024x768 60.00
   1024x576 60.00 59.90 59.82
   960x540 60.00 59.63 59.82
   800x600 60.32 56.25
   864x486 60.00 59.92 59.57
   640x480 59.94
   720x405 59.51 60.00 58.99
   640x360 59.84 59.32 60.00
DP1 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

Good day,

I have tha same issue with my integrated Intel videocard. It comes at first time at spring...still do not know how can solve it. I used to start to reinstall and update packages (sometimes works) or just reinstall Ubuntu.

Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192
LVDS-1 connected primary 1366x768+0+0 (normal left inverted right x axis y axis) 309mm x 174mm
   1366x768 60.03*+ 40.02
   1360x768 59.80 59.96
   1280x720 60.00 59.99 59.86 59.74
   1024x768 60.04 60.00
   960x720 60.00
   928x696 60.05
   896x672 60.01
   1024x576 59.95 59.96 59.90 59.82
   960x600 59.93 60.00
   960x540 59.96 59.99 59.63 59.82
   800x600 60.00 60.32 56.25
   840x525 60.01 59.88
   864x486 59.92 59.57
   800x512 60.17
   700x525 59.98
   800x450 59.95 59.82
   640x512 60.02
   720x450 59.89
   700x450 59.96 59.88
   640x480 60.00 59.94
   720x405 59.51 58.99
   684x384 59.88 59.85
   680x384 59.80 59.96
   640x400 59.88 59.98
   576x432 60.06
   640x360 59.86 59.83 59.84 59.32
   512x384 60.00
   512x288 60.00 59.92
   480x270 59.63 59.82
   400x300 60.32 56.34
   432x243 59.92 59.57
   320x240 60.05
   360x202 59.51 59.13
   320x180 59.84 59.32
VGA-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)

I have the same issue here:

xrandr output:

Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192
LVDS-1 connected primary 1366x768+0+0 (normal left inverted right x axis y axis) 353mm x 198mm
   1366x768 60.00*+
   1360x768 59.80 59.96
   1280x720 60.00 59.99 59.86 59.74
   1024x768 60.04 60.00
   960x720 60.00
   928x696 60.05
   896x672 60.01
   1024x576 59.95 59.96 59.90 59.82
   960x600 59.93 60.00
   960x540 59.96 59.99 59.63 59.82
   800x600 60.00 60.32 56.25
   840x525 60.01 59.88
   864x486 59.92 59.57
   800x512 60.17
   700x525 59.98
   800x450 59.95 59.82
   640x512 60.02
   720x450 59.89
   700x450 59.96 59.88
   640x480 60.00 59.94
   720x405 59.51 58.99
   684x384 59.88 59.85
   680x384 59.80 59.96
   640x400 59.88 59.98
   576x432 60.06
   640x360 59.86 59.83 59.84 59.32
   512x384 60.00
   512x288 60.00 59.92
   480x270 59.63 59.82
   400x300 60.32 56.34
   432x243 59.92 59.57
   320x240 60.05
   360x202 59.51 59.13
   320x180 59.84 59.32
VGA-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
SVIDEO-1 disconnected (normal left inverted right x axis y axis)

FYI, HDMI output works when I switch to a terminal using CTRL_ALT_F3. It seems to not work only in graphics mode.

Same here. Lenovo T460s (Intel only). Cannot use HDMI to Display Port. HDMI to VGA works though on the same port!! The below is with HDMI->VGA. With HDMI->DP it just doesn't recognise the display.

Screen 0: minimum 320 x 200, current 3840 x 2160, maximum 8192 x 8192
eDP-1 connected primary 1920x1080+1233+1080 (normal left inverted right x axis y axis) 309mm x 174mm
   1920x1080 60.02*+ 60.01 59.97 59.96 59.93 50.02
   1680x1050 59.95 59.88
   1600x1024 60.17
   1400x1050 59.98
   1600x900 59.99 59.94 59.95 59.82
   1280x1024 60.02
   1440x900 59.89
   1400x900 59.96 59.88
   1280x960 60.00
   1440x810 60.00 59.97
   1368x768 59.88 59.85
   1360x768 59.80 59.96
   1280x800 59.99 59.97 59.81 59.91
   1152x864 60.00
   1280x720 60.00 59.99 59.86 59.74
   1024x768 60.04 60.00
   960x720 60.00
   928x696 60.05
   896x672 60.01
   1024x576 59.95 59.96 59.90 59.82
   960x600 59.93 60.00
   960x540 59.96 59.99 59.63 59.82
   800x600 60.00 60.32 56.25
   840x525 60.01 59.88
   864x486 59.92 59.57
   800x512 60.17
   700x525 59.98
   800x450 59.95 59.82
   640x512 60.02
   720x450 59.89
   700x450 59.96 59.88
   640x480 60.00 59.94
   720x405 59.51 58.99
   684x384 59.88 59.85
   680x384 59.80 59.96
   640x400 59.88 59.98
   576x432 60.06
   640x360 59.86 59.83 59.84 59.32
   512x384 60.00
   512x288 60.00 59.92
   480x270 59.63 59.82
   400x300 60.32 56.34
   432x243 59.92 59.57
   320x240 60.05
   360x202 59.51 59.13
   320x180 59.84 59.32
DP-1 connected 1920x1080+1920+0 (normal left inverted right x axis y axis) 509mm x 286mm
   1920x1080 60.00*+
   1600x900 60.00
   1280x1024 75.02 60.02
   1152x864 75.00
   1024x768 75.03 60.00
   800x600 75.00 60.32
   640x480 75.00 59.94
   720x400 70.08
HDMI-1 disconnected (normal left inverted right x axis y axis)
   1920x1080 60.02
DP-2 disconnected (normal left inverted right x axis y axis)
HDMI-2 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 509mm x 286mm
   1920x1080 60.00*+ 60.02
   1600x900 60.00
   1280x1024 75.02 60.02
   1152x864 75.00
   1280x720 60.00
   1024x768 75.03 60.00
   800x600 75.00 60.32
   640x480 75.00 59.94
   720x400 70.08

So, seems I have figured out the issue (at least on my Lenovo T460s) and I think it lies with the Intel chip internal GPU.

If you use display port and HDMI-->Display Port adapter it won't work. The Intel chip doesn't seem to support two DP connections at a time. But you can connect Dp & HDMI-->DVI at the same time (or VGA for that matter) & Internal display. So max is 3 displays but they need to be different techs.

I can't confirm this for other laptops without external graphics cards since i don't have any more.

Same here: Asus Zenbook UX410UA, i7-8550U, Intel UHD 620, Ubuntu 18.04.1.

Could those having this issue add their journalctl log from a session where they try to connect the other monitor? And also give details of the video cards/drivers you use and what screen are connected and using what ports/adaptors/etc?

I've got the same problem after the latest update.
My journalctl have no reaction to hdmi connection/disconnection.

But I have reaction for VGA connection:
Jan 24 13:16:48 WinXP gnome-shell[2597]: Object St.Icon (0x55e677b43b90), has been already finalized. Impossible to set any property to it.
Jan 24 13:16:48 WinXP gnome-shell[2597]: Object St.BoxLayout (0x55e677c41390), has been already finalized. Impossible to set any property to it.
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: == Stack trace for context 0x55e67502e320 ==
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #0 0x55e6754c9eb8 i resource:///org/gnome/shell/ui/osdWindow.js:206 (0x7f23880c7780 @ 231)
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #1 0x7ffc48bbf7c0 I resource:///org/gnome/gjs/modules/_legacy.js:82 (0x7f23883b5de0 @ 71)
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #2 0x7ffc48bbf880 b self-hosted:916 (0x7f23883f12b8 @ 367)
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #3 0x7ffc48bbf970 b resource:///org/gnome/gjs/modules/signals.js:128 (0x7f23883d2230 @ 386)
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #4 0x55e6754c9e30 i resource:///org/gnome/shell/ui/layout.js:531 (0x7f23880042b8 @ 127)
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #5 0x7ffc48bc0cd0 b resource:///org/gnome/gjs/modules/_legacy.js:82 (0x7f23883b5de0 @ 71)
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #6 0x7ffc48bc14e0 b self-hosted:916 (0x7f23883f12b8 @ 367)
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: == Stack trace for context 0x55e67502e320 ==
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #0 0x55e6754c9eb8 i resource:///org/gnome/shell/ui/osdWindow.js:207 (0x7f23880c7780 @ 273)
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #1 0x7ffc48bbf7c0 I resource:///org/gnome/gjs/modules/_legacy.js:82 (0x7f23883b5de0 @ 71)
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #2 0x7ffc48bbf880 b self-hosted:916 (0x7f23883f12b8 @ 367)
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #3 0x7ffc48bbf970 b resource:///org/gnome/gjs/modules/signals.js:128 (0x7f23883d2230 @ 386)
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #4 0x55e6754c9e30 i resource:///org/gnome/shell/ui/layout.js:531 (0x7f23880042b8 @ 127)
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #5 0x7ffc48bc0cd0 b resource:///org/gnome/gjs/modules/_legacy.js:82 (0x7f23883b5de0 @ 71)
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #6 0x7ffc48bc14e0 b self-hosted:916 (0x7f23883f12b8 @ 367)
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: == Stack trace for context 0x55e67502e320 ==
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #0 0x55e6754c9eb8 i resource:///org/gnome/shell/ui/osdWindow.js:206 (0x7f23880c7780 @ 231)
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #1 0x7ffc48bbf7c0 I resource:///org/gnome/gjs/modules/_legacy.js:82 (0x7f23883b5de0 @ 71)
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #2 0x7ffc48bbf880 b self-hosted:916 (0x7f23883f12b8 @ 367)
Jan 24 13:16:48 WinXP org.gnome.Shell.desktop[2597]: #3 0x7ffc48bbf970 b resource:///org/gnome/gjs/modules/signals.js:128 (0x7f23883d2230 @ 386)
Jan...

Thought I'd add my 2 cents worth. I only just tried adding a second monitor in addition to my laptop a few days ago and had this problem. Tried many of the suggested solutions - none worked. Works OK in windows 10. Also works OK in 16.04. Tried using a HDMI to digital adapter at the monitor - did not work. OK in windows 10. Alas cannot try the adapter at the computer as no digital or dvi plug. xrandr pretty as in others shown above - HDMI-1 disconnected.
Hopefully this will be fixed before too long.

Still happens here on a HP Pavilion. I have tried the intel onboard video, the nvidia, with the nvidia drivers. If it's of hep the xrandr output shows: HDMI-1 disconnected, so it is seen but not activated. When booting in Windows all works fine...

Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192
eDP-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 382mm x 215mm
   1920x1080 60.02*+ 60.01 59.97 59.96 59.93 40.02
   1680x1050 59.95 59.88
   1600x1024 60.17
   1400x1050 59.98
   1600x900 59.99 59.94 59.95 59.82
   1280x1024 60.02
   1440x900 59.89
   1400x900 59.96 59.88
   1280x960 60.00
   1440x810 60.00 59.97
   1368x768 59.88 59.85
   1360x768 59.80 59.96
   1280x800 59.99 59.97 59.81 59.91
   1152x864 60.00
   1280x720 60.00 59.99 59.86 59.74
   1024x768 60.04 60.00
   960x720 60.00
   928x696 60.05
   896x672 60.01
   1024x576 59.95 59.96 59.90 59.82
   960x600 59.93 60.00
   960x540 59.96 59.99 59.63 59.82
   800x600 60.00 60.32 56.25
   840x525 60.01 59.88
   864x486 59.92 59.57
   800x512 60.17
   700x525 59.98
   800x450 59.95 59.82
   640x512 60.02
   720x450 59.89
   700x450 59.96 59.88
   640x480 60.00 59.94
   720x405 59.51 58.99
   684x384 59.88 59.85
   680x384 59.80 59.96
   640x400 59.88 59.98
   576x432 60.06
   640x360 59.86 59.83 59.84 59.32
   512x384 60.00
   512x288 60.00 59.92
   480x270 59.63 59.82
   400x300 60.32 56.34
   432x243 59.92 59.57
   320x240 60.05
   360x202 59.51 59.13
   320x180 59.84 59.32
HDMI-1 disconnected (normal left inverted right x axis y axis)

I can also confirm the problem. The Ubuntu 18.04LTS (updated everything) does NOT sense when I disconnect the HDMI. There is no change in /sys. This uis the mainb problem, I guess. The events does not generate screen switching.

Very annoying when the screen locked and disconnected from external monitor, the notebook display remaions black!

I checked the status, and it STILL shown connected but the HDMI monitor was disconnected:

----
root@notebook:~# cat /sys/class/drm/card0-HDMI-A-1/status
connected
root@notebook:~# cat /sys/class/drm/card0-HDMI-A-1/status
connected
root@notebook:~# cat /sys/class/drm/card0-HDMI-A-1/status

----

HW: Dell Lattitude 7490
----

Sometimes work, sometimes NOT.

It is very annoying when I work with the notebook, it's screen remains black after I disconnect the external monitor. I created Keyboard shortucts to force screen UP:

Lspci:
00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v6/7th Gen Core Processor Host Bridge/DRAM Registers (rev 02)
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 620 (rev 02)
00:04.0 Signal processing controller: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Thermal Subsystem (rev 02)
00:14.0 USB controller: Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller (rev 21)
00:14.2 Signal processing controller: Intel Corporation Sunrise Point-LP Thermal subsystem (rev 21)
00:15.0 Signal processing controller: Intel Corporation Sunrise Point-LP Serial IO I2C Controller #0 (rev 21)
00:15.1 Signal processing controller: Intel Corporation Sunrise Point-LP Serial IO I2C Controller #1 (rev 21)
00:15.2 Signal processing controller: Intel Corporation Sunrise Point-LP Serial IO I2C Controller #2 (rev 21)
00:15.3 Signal processing controller: Intel Corporation Sunrise Point-LP Serial IO I2C Controller #3 (rev 21)
00:16.0 Communication controller: Intel Corporation Sunrise Point-LP CSME HECI #1 (rev 21)
00:16.3 Serial controller: Intel Corporation Device 9d3d (rev 21)
00:17.0 SATA controller: Intel Corporation Sunrise Point-LP SATA Controller [AHCI mode] (rev 21)
00:1c.0 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #1 (rev f1)
00:1c.2 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #3 (rev f1)
00:1f.0 ISA bridge: Intel Corporation Intel(R) 100 Series Chipset Family LPC Controller/eSPI Controller - 9D4E (rev 21)
00:1f.2 Memory controller: Intel Corporation Sunrise Point-LP PMC (rev 21)
00:1f.3 Audio device: Intel Corporation Sunrise Point-LP HD Audio (rev 21)
00:1f.4 SMBus: Intel Corporation Sunrise Point-LP SMBus (rev 21)
00:1f.6 Ethernet controller: Intel Corporation Ethernet Connection (4) I219-LM (rev 21)
01:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS525A PCI Express Card Reader (rev 01)
02:00.0 Network controller: Intel Corporation Wireless 8265 / 8275 (rev 78)

------
root@notebook:~# uname -a
Linux notebook 4.18.0-16-generic #17~18.04.1-Ubuntu SMP Tue Feb 12 13:35:51 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
------

Im having a similar problem. I have a ThinkPad T520, running xfce 4.12 on ubuntu 18.04.

I have tried this command with and without '--auto':

'xrandr --output LVDS-1 --auto --same-as DP-1-1'

Here is my xrandr output:

Screen 0: minimum 320 x 200, current 1600 x 900, maximum 8192 x 8192
LVDS-1 connected primary 1600x900+0+0 (normal left inverted right x axis y axis) 345mm x 194mm
   1600x900 59.99*+ 59.99 59.94 59.95 59.82 50.00
   1440x900 59.89
   1400x900 59.96 59.88
   1440x810 60.00 59.97
   1368x768 59.88 59.85
   1360x768 59.80 59.96
   1280x800 59.99 59.97 59.81 59.91
   1152x864 60.00
   1280x720 60.00 59.99 59.86 59.74
   1024x768 60.04 60.00
   960x720 60.00
   928x696 60.05
   896x672 60.01
   1024x576 59.95 59.96 59.90 59.82
   960x600 59.93 60.00
   960x540 59.96 59.99 59.63 59.82
   800x600 60.00 60.32 56.25
   840x525 60.01 59.88
   864x486 59.92 59.57
   800x512 60.17
   700x525 59.98
   800x450 59.95 59.82
   640x512 60.02
   720x450 59.89
   700x450 59.96 59.88
   640x480 60.00 59.94
   720x405 59.51 58.99
   684x384 59.88 59.85
   680x384 59.80 59.96
   640x400 59.88 59.98
   576x432 60.06
   640x360 59.86 59.83 59.84 59.32
   512x384 60.00
   512x288 60.00 59.92
   480x270 59.63 59.82
   400x300 60.32 56.34
   432x243 59.92 59.57
   320x240 60.05
   360x202 59.51 59.13
   320x180 59.84 59.32
VGA-1 disconnected (normal left inverted right x axis y axis)
LVDS-1-2 disconnected (normal left inverted right x axis y axis)
VGA-1-2 disconnected (normal left inverted right x axis y axis)
DP-1-1 connected (normal left inverted right x axis y axis)
   1920x1080 60.00 + 50.00 59.94
   1920x1080i 60.00 50.00 59.94
   1680x1050 59.88
   1600x900 60.00
   1280x1024 75.02 60.02
   1280x800 59.91
   1152x864 75.00
   1280x720 60.00 50.00 59.94
   1024x768 75.03 60.00
   832x624 74.55
   800x600 75.00 60.32
   720x576 50.00
   720x480 60.00 59.94
   640x480 75.00 60.00 59.94
   720x400 70.08
DP-1-2 disconnected (normal left inverted right x axis y axis)
DP-1-3 disconnected (normal left inverted right x axis y axis)
  1280x800 (0x51) 71.000MHz +HSync -VSync
        h: width 1280 start 1328 end 1360 total 1440 skew 0 clock 49.31KHz
        v: height 800 start 803 end 809 total 823 clock 59.91Hz
  1024x768 (0x57) 65.000MHz -HSync -VSync
        h: width 1024 start 1048 end 1184 total 1344 skew 0 clock 48.36KHz
        v: height 768 start 771 end 777 total 806 clock 60.00Hz
  800x600 (0x5a) 40.000MHz +HSync +VSync
        h: width 800 start 840 end 968 total 1056 skew 0 clock 37.88KHz
        v: height 600 start 601 end 605 t...

For me, updating drivers solved the issue. I have got Intel controller:

$ lspci | grep VGA

00:02.0 VGA compatible controller: Intel Corporation HD Graphics 620 (rev 02)

This is how to update drivers:

sudo add-apt-repository ppa:oibaf/graphics-drivers

sudo apt-get install xserver-xorg-video-intel

hope this helps.

Also affecting me. Dell Inspiron 5379

Linux danny-Inspiron-5379 5.0.0-13-generic #14-Ubuntu SMP Mon Apr 15 14:59:14 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=19.04
DISTRIB_CODENAME=disco
DISTRIB_DESCRIPTION="Ubuntu 19.04"

I got it fixed after upgrading from 18.04 to 19.04, but it was not upgrading that solved it. The issue is still there in 19.04.

The solution for me was disabling secure boot, purging the nvidia drivers and then reïnstalling them.

Apparently when secure boot is on, the nvidia-drivers do get installed, (and they show as in use by the GUI provided for it in Ubuntu) but do not get loaded. I figured this out when running nvidia-settings from terminal. It showed an error: nvidia not loaded.

In other words, if a developer is watching this, there are two bugs:
- 'not loading of the nvidia drivers' when secure boot is on.
- The hardware drivers GUI in 'software and updates', shows the proprietary driver is in use, while it is not, it's only installed, but not running.

I hope this helps.

I can confirm that the drivers don't get loaded in 18.04 even though they are installed. This is also what I get when running nvidia-settings from terminal.
ERROR: NVIDIA driver is not loaded
ERROR: Unable to load info from any available system

$uname -a
Linux laptop 4.18.0-25-generic #26~18.04.1-Ubuntu SMP Thu Jun 27 07:28:31 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

I have similar problem.

imac 27" with Ubuntu 18.04 LTS, 4.18.0-25-generic
Thunderbolt display
VGA compatible controller: NVIDIA Corporation GK104M [GeForce GTX 775M Mac Edition] (rev a1)

Sometimes, after logging in, both screens are on.
After shutdown, the second screen sometimes is off.
Then, I have to restart and it could or couldn't work.

Looks like random behavior.

It would be good to have the second screen on since the boot startup.

I have similar problem.

Acer Aspire VN7-792G with Nvida GeForce 960M and Ubuntu 18.04.2 LTS.
Try to connect to monitor Asus vx239h.

Sometimes it turns out to connect a second screen as an extension of the screen, for example, if you go into console mode and return. It works for a while, when you try to enter Settings, the screen turns off.

I upgraded my system to the 5.0 kernel of 18.04.3 recently, but the external monitor is still not detected and also xrandr still lists HDMI as disconnected. I was hoping badly for an improvement, but so far it does not seem as if someone is working on this bug.

Just upgraded to 18.04.03 and thought I'd check if there was any action on this, but alas, no change. I see you were asking for a journalctl dump. Here's mine from today attached. H/W & driver details are:-
  *-display UNCLAIMED
       description: VGA compatible controller
       product: GP106M [GeForce GTX 1060 Mobile]
       vendor: NVIDIA Corporation
       physical id: 0
       bus info: pci@0000:01:00.0
       version: a1
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress vga_controller bus_master cap_list
       configuration: latency=0
       resources: memory:a3000000-a3ffffff memory:90000000-9fffffff memory:a0000000-a1ffffff ioport:4000(size=128) memory:a4000000-a407ffff
  *-display
       description: VGA compatible controller
       product: Intel Corporation
       vendor: Intel Corporation
       physical id: 2
       bus info: pci@0000:00:02.0
       version: 00
       width: 64 bits
       clock: 33MHz
       capabilities: pciexpress msi pm vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:28 memory:a2000000-a2ffffff memory:80000000-8fffffff ioport:5000(size=64) memory:c0000-dffff

Hopefully this is what you are after.
Regards

Playing with different resolutions and rates using xrandr solved the problem for me on a DELL XPS 15 with Ubuntu 18.04. If I go with a resolution of 1920x1080 and a rate of 60 Hz the TV shows a black screen. Changing to other modes and rates solves the problem. For example, typing in a terminal

    xrandr --output DP-1-3 --mode 1360x768 --rate 60

made it work. If I go for a resolution of 1920x1080, I have output only for a rate of 25 Hz. I don't know why exactly this happens. Maybe it depends on the TV?