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I have my Ubuntu 19.10 HTPC plugged-in to a HDMI switch, which then routes to my monitor. Most of the time that HDMI switch is set to my Nvidia ShieldTV streaming device, and the TV is off.

When I VNC into my HTPC, I am often unable to do anything on the screen. Mouse and keyboard inputs through VNC are completely ignored. Looking through syslog, I found a "monitor is undefined" error.

Oct 21 15:37:30 myhost gnome-shell[1119]: JS ERROR: Extension dash-to-panel@jderose9.github.com: TypeError: monitor is undefined#012checkIfFocusedMonitor@/home/myuser/.local/share/gnome-shell/extensions/dash-to-panel@jderose9.github.com/panelManager.js:266:9#012_adjustForOverview@/home/myuser/.local/share/gnome-shell/extensions/dash-to-panel@jderose9.github.com/panel.js:429:32#012enable@/home/myuser/.local/share/gnome-shell/extensions/dash-to-panel@jderose9.github.com/panel.js:112:9#012enable@/home/myuser/.local/share/gnome-shell/extensions/dash-to-panel@jderose9.github.com/panelManager.js:72:9#012_enable@/home/myuser/.local/share/gnome-shell/extensions/dash-to-panel@jderose9.github.com/extension.js:91:5#012enable@/home/myuser/.local/share/gnome-shell/extensions/dash-to-panel@jderose9.github.com/extension.js:63:5#012_callExtensionEnable@resource:///org/gnome/shell/ui/extensionSystem.js:132:13#012loadExtension@resource:///org/gnome/shell/ui/extensionSystem.js:264:21#012_loadExtensions/<@resource:///org/gnome/shell/ui/extensionSystem.js:482:13#012collectFromDatadirs@resource:///org/gnome/shell/misc/fileUtils.js:27:17#012_loadExtensions@resource:///org/gnome/shell/ui/extensionSystem.js:457:9#012_enableAllExtensions@resource:///org/gnome/shell/ui/extensionSystem.js:491:13#012_sessionUpdated@resource:///org/gnome/shell/ui/extensionSystem.js:522:13#012init@resource:///org/gnome/shell/ui/extensionSystem.js:32:9#012_initializeUI@resource:///org/gnome/shell/ui/main.js:245:5#012start@resource:///org/gnome/shell/ui/main.js:141:5#012@<main>:1:31

Sure enough, when I turned the TV on everything immediately starts to work after a systemctl restart gdm (which did not work previously).

From my research, I found this question below which addresses running Ubuntu headless.

How to use Ubuntu 18.04 on VNC without display attached?

However I am not running headless, I have a monitor attached, it's just turned off. Any way to make this work at the X/Gnome level?

Additionally I tried disabling all Gnome extensions entirely in the tweak tool and the problem still happened. So this is not an extension problem.

Georg
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1 Answers1

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I suffered the same issue: Ubuntu 18.04 with x11vnc. Turn off monitor and VNC client at the other side freezes, turn on again and it works fine.

Fix/Workaround: replace the HDMI to HDMI cable from pc to monitor with a DVI to DVI cable from pc to monitor. Now turning off and on the monitor does not influence the VNC client anymore.

Do not ask why, it just works now.

uraura00
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