NoMachine freezing on XFCE (Xubuntu) Linux?

[rcragun]

I’ve been running NoMachine on my headless fileserver (so, virtual display) for several years. I recently had to reformat my fileserver and install all the software on it fresh. When I did, I started getting a weird error with NoMachine: after anywhere from 5 to 10 minutes with an open session, the screen would freeze (sort of). My cursor would no longer click on anything. I could still SSH into my fileserver separately and do pretty much anything from a terminal, but the NoMachine session was basically useless until I rebooted my computer.

I thought it might be the screensaver or power settings, so I turned those off completely. Now, the screensaver should not be kicking on. The screen should not be shutting off after a specific time period. Etc. But NoMachine still freezes.

To make sure this wasn’t a client issue, I tried logging in with a different computer (my laptop) and had the same issue happen. And, in fact, when I logged in from my laptop after the screen had frozen on my desktop, it was frozen on my laptop. So, it appears to be a NoMachine server issue, not a client issue.

I then tried adjusting the Server performance settings, turning off “Use a specific display encoding,” “Use hardware encoding,” and “Use acceleration for display processing.” I did each of those separately then all together, and the error happened again.

I’ve spent about a week trying to troubleshoot this and finally found something on the NoMachine forums that has made it so I at least don’t have to reboot every time I want to run NoMachine. This Knowledge Base answer shows how to restart lightdm from the terminal: https://kb.nomachine.com/TR03T10500 I tried that, and suddenly I could use the NoMachine session again without rebooting the computer. But the session freezes again after about 5 minutes, requiring another restart of lightdm to use NoMachine.

Some information to help…

Server:

Xubuntu 22.04.3 (custom-built computer)

NoMachine 8.8.1

Client:

Kubuntu 22.04 (custom-built computer)

NoMachine 8.8.1

I’m not really sure what else to try at this point. Any suggestions on what might be causing NoMachine to freeze every 5 to 10 minutes on XFCE?

[fra81]

Hi,

do you have a Nvidia card on the server? In that case you may try the suggestion in this article: https://kb.nomachine.com/AR12T01182.

If that doesn’t help, please gather server side logs by following the instructions in https://kb.nomachine.com/DT07S00243. You can send the logs to forum[at]nomachine[dot]com.

[rcragun]

I do have an NVidia card in the fileserver. I tried adjusting the settings in my xorg.conf file as indicated in the suggested article and it didn’t solve the problem. 🙁

I have just emailed the log files from the server.

[fra81]

It seems your graphics card goes into some low power mode. Very likely not something that can be controlled programmatically. I’d try one of the suggestions in this article: https://kb.nomachine.com/AR03P00973.

But before that, it would be nice to gather some more info on the system status. Do you have the possibility to ssh into the server and show the output of the following commands?

DISPLAY=:0 xset -q

DISPLAY=:0 xrandr --verbose

If possible, run the commands both before and after the problem occurs.

And finally, what system was installed on the server before you reinstalled it?

[rcragun]

I appreciate your help.

Here are the results of those commands via SSH…

First command with the screen frozen:

$ DISPLAY=:0 xset -q
Keyboard Control:
auto repeat:  on    key click percent:  0    LED mask:  00000002
XKB indicators:
00: Caps Lock:   off    01: Num Lock:    on     02: Scroll Lock: off
03: Compose:     off    04: Kana:        off    05: Sleep:       off
06: Suspend:     off    07: Mute:        off    08: Misc:        off
09: Mail:        off    10: Charging:    off    11: Shift Lock:  off
12: Group 2:     off    13: Mouse Keys:  off
auto repeat delay:  500    repeat rate:  20
auto repeating keys:  00ffffffdffffbbf
fadfffefffedffff
9fffffffffffffff
fff7ffffffffffff
bell percent:  50    bell pitch:  400    bell duration:  100
Pointer Control:
acceleration:  2/1    threshold:  4
Screen Saver:
prefer blanking:  no    allow exposures:  no
timeout:  300    cycle:  300
Colors:
default colormap:  0x20    BlackPixel:  0x0    WhitePixel:  0xffffff
Font Path:
/usr/share/fonts/X11/misc,/usr/share/fonts/X11/Type1,built-ins
DPMS (Energy Star):
Standby: 0    Suspend: 0    Off: 0
DPMS is Enabled
Monitor is On

First command with the screen not frozen:

$ DISPLAY=:0 xset -q           
Keyboard Control:
auto repeat:  on    key click percent:  0    LED mask:  00000002
XKB indicators:
00: Caps Lock:   off    01: Num Lock:    on     02: Scroll Lock: off
03: Compose:     off    04: Kana:        off    05: Sleep:       off
06: Suspend:     off    07: Mute:        off    08: Misc:        off
09: Mail:        off    10: Charging:    off    11: Shift Lock:  off
12: Group 2:     off    13: Mouse Keys:  off
auto repeat delay:  500    repeat rate:  20
auto repeating keys:  00ffffffdffffbbf
fadfffefffedffff
9fffffffffffffff
fff7ffffffffffff
bell percent:  50    bell pitch:  400    bell duration:  100
Pointer Control:
acceleration:  2/1    threshold:  4
Screen Saver:
prefer blanking:  no    allow exposures:  no
timeout:  300    cycle:  300
Colors:
default colormap:  0x20    BlackPixel:  0x0    WhitePixel:  0xffffff
Font Path:
/usr/share/fonts/X11/misc,/usr/share/fonts/X11/Type1,built-ins
DPMS (Energy Star):
Standby: 0    Suspend: 0    Off: 0
DPMS is Enabled
Monitor is On

 

Second command with the screen frozen:

$ DISPLAY=:0 xrandr –verbose
Screen 0: minimum 8 x 8, current 1680 x 1050, maximum 32767 x 32767
DVI-D-0 disconnected primary (normal left inverted right x axis y axis)
Identifier: 0x1bc
Timestamp:  2231482
Subpixel:   unknown
Clones:
CRTCs:      0 1 2 3
Transform:  1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0
0 1
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
SignalFormat: TMDS
supported: TMDS
ConnectorType: DVI-D
ConnectorNumber: 0
_ConnectorLocation: 0
non-desktop: 0
supported: 0, 1
HDMI-0 disconnected (normal left inverted right x axis y axis)
Identifier: 0x1bd
Timestamp:  2231482
Subpixel:   unknown
Clones:
CRTCs:      0 1 2 3
Transform:  1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0
0 1
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
SignalFormat: TMDS
supported: TMDS
ConnectorType: HDMI
ConnectorNumber: 3
_ConnectorLocation: 3
non-desktop: 0
supported: 0, 1
DP-0 disconnected (normal left inverted right x axis y axis)
Identifier: 0x1be
Timestamp:  2231482
Subpixel:   unknown
Clones:
CRTCs:      0 1 2 3
Transform:  1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0
0 1
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
SignalFormat: DisplayPort
supported: DisplayPort
ConnectorType: DisplayPort
ConnectorNumber: 4
_ConnectorLocation: 4
non-desktop: 0
supported: 0, 1
DP-1 disconnected (normal left inverted right x axis y axis)
Identifier: 0x1bf
Timestamp:  2231482
Subpixel:   unknown
Clones:
CRTCs:      0 1 2 3
Transform:  1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0
0 1
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
SignalFormat: TMDS
supported: TMDS
ConnectorType: DisplayPort
ConnectorNumber: 4
_ConnectorLocation: 4
non-desktop: 0
supported: 0, 1
DP-2 disconnected (normal left inverted right x axis y axis)
Identifier: 0x1c0
Timestamp:  2231482
Subpixel:   unknown
Clones:
CRTCs:      0 1 2 3
Transform:  1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0
0 1
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
SignalFormat: DisplayPort
supported: DisplayPort
ConnectorType: DisplayPort
ConnectorNumber: 2
_ConnectorLocation: 2
non-desktop: 0
supported: 0, 1
DP-3 disconnected (normal left inverted right x axis y axis)
Identifier: 0x1c1
Timestamp:  2231482
Subpixel:   unknown
Clones:
CRTCs:      0 1 2 3
Transform:  1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0
0 1
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
SignalFormat: TMDS
supported: TMDS
ConnectorType: DisplayPort
ConnectorNumber: 2
_ConnectorLocation: 2
non-desktop: 0
supported: 0, 1
DP-4 disconnected (normal left inverted right x axis y axis)
Identifier: 0x1c2
Timestamp:  2231482
Subpixel:   unknown
Clones:
CRTCs:      0 1 2 3
Transform:  1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0
0 1
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
SignalFormat: DisplayPort
supported: DisplayPort
ConnectorType: DisplayPort
ConnectorNumber: 1
_ConnectorLocation: 1
non-desktop: 0
supported: 0, 1
DP-5 disconnected (normal left inverted right x axis y axis)
Identifier: 0x1c3
Timestamp:  2231482
Subpixel:   unknown
Clones:
CRTCs:      0 1 2 3
Transform:  1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0
0 1
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
SignalFormat: TMDS
supported: TMDS
ConnectorType: DisplayPort
ConnectorNumber: 1
_ConnectorLocation: 1
non-desktop: 0
supported: 0, 1

And the second command with the screen not frozen:

$ DISPLAY=:0 xrandr –verbose  
Screen 0: minimum 8 x 8, current 1680 x 1050, maximum 32767 x 32767
DVI-D-0 disconnected primary (normal left inverted right x axis y axis)
Identifier: 0x1bc
Timestamp:  86611532
Subpixel:   unknown
Clones:
CRTCs:      0 1 2 3
Transform:  1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0
0 1
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
SignalFormat: TMDS
supported: TMDS
ConnectorType: DVI-D
ConnectorNumber: 0
_ConnectorLocation: 0
non-desktop: 0
supported: 0, 1
HDMI-0 disconnected (normal left inverted right x axis y axis)
Identifier: 0x1bd
Timestamp:  86611532
Subpixel:   unknown
Clones:
CRTCs:      0 1 2 3
Transform:  1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0
0 1
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
SignalFormat: TMDS
supported: TMDS
ConnectorType: HDMI
ConnectorNumber: 3
_ConnectorLocation: 3
non-desktop: 0
supported: 0, 1
DP-0 disconnected (normal left inverted right x axis y axis)
Identifier: 0x1be
Timestamp:  86611532
Subpixel:   unknown
Clones:
CRTCs:      0 1 2 3
Transform:  1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0
0 1
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
SignalFormat: DisplayPort
supported: DisplayPort
ConnectorType: DisplayPort
ConnectorNumber: 4
_ConnectorLocation: 4
non-desktop: 0
supported: 0, 1
DP-1 disconnected (normal left inverted right x axis y axis)
Identifier: 0x1bf
Timestamp:  86611532
Subpixel:   unknown
Clones:
CRTCs:      0 1 2 3
Transform:  1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0
0 1
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
SignalFormat: TMDS
supported: TMDS
ConnectorType: DisplayPort
ConnectorNumber: 4
_ConnectorLocation: 4
non-desktop: 0
supported: 0, 1
DP-2 disconnected (normal left inverted right x axis y axis)
Identifier: 0x1c0
Timestamp:  86611532
Subpixel:   unknown
Clones:
CRTCs:      0 1 2 3
Transform:  1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0
0 1
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
SignalFormat: DisplayPort
supported: DisplayPort
ConnectorType: DisplayPort
ConnectorNumber: 2
_ConnectorLocation: 2
non-desktop: 0
supported: 0, 1
DP-3 disconnected (normal left inverted right x axis y axis)
Identifier: 0x1c1
Timestamp:  86611532
Subpixel:   unknown
Clones:
CRTCs:      0 1 2 3
Transform:  1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0
0 1
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
SignalFormat: TMDS
supported: TMDS
ConnectorType: DisplayPort
ConnectorNumber: 2
_ConnectorLocation: 2
non-desktop: 0
supported: 0, 1
DP-4 disconnected (normal left inverted right x axis y axis)
Identifier: 0x1c2
Timestamp:  86611532
Subpixel:   unknown
Clones:
CRTCs:      0 1 2 3
Transform:  1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0
0 1
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
SignalFormat: DisplayPort
supported: DisplayPort
ConnectorType: DisplayPort
ConnectorNumber: 1
_ConnectorLocation: 1
non-desktop: 0
supported: 0, 1
DP-5 disconnected (normal left inverted right x axis y axis)
Identifier: 0x1c3
Timestamp:  86611532
Subpixel:   unknown
Clones:
CRTCs:      0 1 2 3
Transform:  1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0
0 1
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
SignalFormat: TMDS
supported: TMDS
ConnectorType: DisplayPort
ConnectorNumber: 1
_ConnectorLocation: 1
non-desktop: 0
supported: 0, 1

It looks like DPMS is on, which I set to be off in the xorg.conf file. Odd. Not sure why DPMS is on when I specifically set the xorg.conf file to not allow it to turn on. Hmmm… I’m going to play with this. I think I found a way to turn off DPMS. I wonder if I turn that off if it will fix the problem. I will return and report!

As for the previous system – exact same setup – Xubuntu. I had to reformat it because I was playing with some other software on the fileserver and, in the process, screwed up a bunch of stuff. I literally copied my xorg.conf file over from the previous installation. Not sure why it isn’t working this time.

[rcragun]

I figured I’d try turning off DPMS to see if that was the problem. I restarted lightdm then turned off DPMS manually and it still froze. So, DPMS is not the problem.

[rcragun]

Update: I changed my Nvidia driver from 535 (the latest, recommended driver that was installed by default) to 470 and the problem went away. Not sure what it is about the latest Nvidia driver but it isn’t playing nice with NoMachine on XFCE.

[rcragun]

Update to my Update: Switching Nvidia drivers didn’t solve it. It took a lot longer to freeze up (several hours this time), but the screen, once again, froze. Back to troubleshooting.

[rcragun]

I finally solved the problem. The system settings dialog for power management wasn’t actually changing the XML file that dictated power management settings.

 

The actual settings to manage the power in XFCE are located here:

/home/[user]/.config/xfce4/xfconf/xfce-perchannel-xml/xfce4-power-manager.xml

Opening that file with a text editor, I looked for any instance where the setting didn’t make sense. And, sure enough, there was a problem. On this line, I had a “3” when I should have had a “0.”

<property name="blank-on-ac" type="int" value="3"/>

In this file, “0” means “never,” which would tell the computer to never blank the screen when on AC power. I’m assuming “3” means after 5 minutes. So, despite me using the Power Management interface to tell XFCE to never blank the screen on AC power, that setting did NOT get updated in the actual file that controls this. I changed the value manually in the text editor and restarted my computer.

And, problem solved. NoMachine is no longer freezing up due to XFCE blanking the screen on AC and going into a low power mode.

[Author]

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