After disconnect, physical screen always stays black (on 9.3.7)

[rbuehlma]

I’m facing exactly the same issue as described in After disconnect, physical screen always stays black – NoMachine Forum but on the current version of NoMachine Enterprise Desktop.

TR12M06302 has been released for Version 5 but not for 9. Is the same issue also present in Version 9? Will this fix released for this version as well (and if yes, do you have an ETA for it?) or could it be a different issue?

If it is a different issue, please let me know which information I can provide to debug the issue.

Client & Server:
NoMachine Enterprise Desktop version 9.3.7
Ubuntu 25.10 running Gnome on Wayland

[Britgirl]

Hello, the problem you are encountering is most likely being caused by something else. Can you confirm the exact steps to reproduce the problem? Are you using multi-monitors? Also, a full set of logs which you can attach here (https://kb.nomachine.com/DT08U00298#1.1) or send directly to forum[at]nomachine[dot]com. If you choose to send via email, please use the title of this topic as the subject. Thanks!

[rbuehlma]

These are the steps I take:

– Start the PC and work locally
– Lock screen when leaving
– Login from remote
– Disable second monitor in Gnome settings (since my remote station has only one screen)
– Terminate NoMachine session (Local screen gets locked)
– Login locally
– Re-enable second monitor -> Monitor gets active but stays black

I will provide the logs by email.

[Britgirl]

Just to let you know we got the logs and are currently investigating.

[fra81]

Hi @rbuehlma,

can you show the output of these commands (you can copy the output to a file) taken while the monitor is black?

gdbus call --session --dest org.gnome.Mutter.DisplayConfig --object-path /org/gnome/Mutter/DisplayConfig --method org.gnome.Mutter.DisplayConfig.GetCurrentState
gdbus call --session --dest org.gnome.Mutter.DisplayConfig --object-path /org/gnome/Mutter/DisplayConfig --method org.gnome.Mutter.DisplayConfig.GetResources

Does disabling and re-enabling the second monitor (without connecting remotely) help to make the monitor visible again?

[rbuehlma]

Sure, attached are the two files.

Disabling and re-enabling the second monitor does not help (I tried it through the gnome display manager).

One additionaly observation:

When connecting through NoMachine but still having the second monitor active, I can see in NoMachine that the second monitor is already black at that time.

Attachments:

1. GetResources.txt
2. GetCurrentState.txt

[fra81]

Hello, we tried to reproduce this issue without success. It actually seems more like a system issue than a NoMachine issue.

Regarding the steps you mentioned before:

– Start the PC and work locally
– Lock screen when leaving
– Login from remote
– Disable second monitor in Gnome settings (since my remote station has only one screen)
– Terminate NoMachine session (Local screen gets locked)
– Login locally
– Re-enable second monitor -> Monitor gets active but stays black

Please try to change those steps by re-enabling the second monitor before terminating the NoMachine session, i.e.:

– Start the PC and work locally
– Lock screen when leaving
– Login from remote
– Disable second monitor in Gnome settings (since my remote station has only one screen)
– Re-enable second monitor
– Terminate NoMachine session (Local screen gets locked)
– Login locally

Is the monitor black when you will login locally?

[rbuehlma]

I tried this as well an yes, the monitor stays black in this case as well.

I also tried to disable the second monitor before connecting through NoMachine and enabling the monitor when back local and there as well, the screen remains black. But this only happens if I connect with NoMachine in between. If I simply disable and re-enable the screen locally, there is no issue.

[fra81]

We see this in the logs:

(process:6599): dconf-CRITICAL **: 14:50:08.603: unable to create file ‘/home/rbuehlma/.cache/dconf/user’: Permission denied. dconf will not work properly

You could try to adjust the permissions for the ‘/home/rbuehlma/.cache/dconf’ dir until that error in the logs goes away. It is normally owned by the logged-in user with 700 permissions.

And did you enable the ‘Blank the physical screen when somebody connects’ option? If that is the case, please try to disable it and see if the problem persists.

[rbuehlma]

I’m sorry, it took me some time to test these cases:

The permission problem is fixed but the problem still persists.

Disabling the option ‘Blank the physical screen when somebody connects’ does solve the issue but not having the remote screen blanked/locked is not an option in my case.

I now also updated to nomachine 9.4.14 but there the problem persists as well.

[Britgirl]

You don’t have to disable the second monitor, you can leave it enabled and the use the NoMachine player to select the monitor you want. We’ll continue to investigate, we’ve been unable to reproduce so far.

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