display error back again?

[cmdrKEEN]

I just tested the new image and got this:

pi@qlcplus:~ $ sudo qlcplus service status
qt.qpa.xcb: could not connect to display
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, xcb.

Aborted

hdmi_force_hotplug=1 does not seem to work in bookworm

as soon as I plug in a monitor it continues to start

[mcallegari]

Thanks for reporting.
Unfortunately I can confirm this is back (damnit!)
I haven't tried it yet, but maybe using another platform plugin will help.
Edit

Code: Select all

/usr/sbin/qlcplus-start.sh

and replace

Code: Select all

-platform eglfs

with

Code: Select all

-platform offscreen

or

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-platform linuxfb

If anyone tries before me, please report if it works

[fnupp]

Worked for me I tried both the following

-platform offscreen
and
-platform vnc

[mcallegari]

Great, thank you.
At least we have a workaround while we wait for an official solution from the RPi foundation devs.

[cheltgar]

Hi

I have run into the same error - now getting the same message from the qlcplus service call.

I have implemented the change above, and this seems to resolve the problem, I now get the Web Page, but im not confident I have implemented the change correctly, and won't run into other problems down the line because of it.
Could someone more knowledgeable please check what I have done

My Original file looked like this (with the comments out at the beginning removed)

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QLCPLUS_OPTS="-platform eglfs --nowm --web --web-auth --operate --overscan"

if [ ! -f $HOME/.qlcplus/eglfs.json ]; then
    mkdir -p $HOME/.qlcplus
    echo '{ "device": "/dev/dri/card1" }' > $HOME/.qlcplus/eglfs.json
fi

if [ -f $HOME/.qlcplus/autostart.qxw ]; then
    QLCPLUS_OPTS="$QLCPLUS_OPTS --open $HOME/.qlcplus/autostart.qxw"
fi

# if NTP hasn't done its job already, set the date to modern age...
CURRDATE=`date +%Y`
if [ "$CURRDATE" -lt "2024" ]; then
    date +%Y%m%d -s "20240313"
fi

export QT_QPA_EGLFS_PHYSICAL_WIDTH=320
export QT_QPA_EGLFS_PHYSICAL_HEIGHT=200
export QT_QPA_EGLFS_ALWAYS_SET_MODE=1
export QT_QPA_EGLFS_KMS_CONFIG=$HOME/.qlcplus/eglfs.json

/usr/bin/qlcplus $QLCPLUS_OPTS

And my modified (now working) file looks like this

Code: Select all

QLCPLUS_OPTS="-platform offscreen"
#eglfs --nowm --web --web-auth --operate --overscan"

#if [ ! -f $HOME/.qlcplus/eglfs.json ]; then
#    mkdir -p $HOME/.qlcplus
#    echo '{ "device": "/dev/dri/card1" }' > $HOME/.qlcplus/eglfs.json
#fi

#if [ -f $HOME/.qlcplus/autostart.qxw ]; then
#    QLCPLUS_OPTS="$QLCPLUS_OPTS --open $HOME/.qlcplus/autostart.qxw"
#fi

# if NTP hasn't done its job already, set the date to modern age...
CURRDATE=`date +%Y`
if [ "$CURRDATE" -lt "2024" ]; then
    date +%Y%m%d -s "20240313"
fi

#export QT_QPA_EGLFS_PHYSICAL_WIDTH=320
#export QT_QPA_EGLFS_PHYSICAL_HEIGHT=200
#export QT_QPA_EGLFS_ALWAYS_SET_MODE=1
#export QT_QPA_EGLFS_KMS_CONFIG=$HOME/.qlcplus/eglfs.json

/usr/bin/qlcplus $QLCPLUS_OPTS

Could someone please confirm if this is the correct way to change the file n- or should I have left more uncommented - especially the parameters on the first line.

thanks

Gareth

[mcallegari]

No, the first line should look like this:

Code: Select all

QLCPLUS_OPTS="-platform offscreen --nowm --web --web-auth --operate --overscan"

[cheltgar]

Great - thanks for the information - will adjust
KR
Gareth

[ohbcIT]

Moving from Ubuntu 22.04 to 24.04 and from qlcplus 4.12.4 to 4.12.7 yielded us an error with a log entry like this :

May 02 23:21:24 ohbc-lighting systemd[1]: Started qlcplus.service - Oak Hills Baptist Church Lighting Controller.
May 02 23:21:45 ohbc-lighting qlcplus[2471]: Authorization required, but no authorization protocol specified
May 02 23:21:45 ohbc-lighting qlcplus[2471]: qt.qpa.xcb: could not connect to display :0
May 02 23:21:45 ohbc-lighting qlcplus[2471]: qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.
May 02 23:21:45 ohbc-lighting qlcplus[2471]: This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
May 02 23:21:45 ohbc-lighting qlcplus[2471]: Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, xcb.
May 02 23:22:11 ohbc-lighting systemd[1]: qlcplus.service: Main process exited, code=dumped, status=6/ABRT
May 02 23:22:11 ohbc-lighting systemd[1]: qlcplus.service: Failed with result 'core-dump'.

After a bit of experimentation these changes in our custom systemd qlcplus.service got us over the top :

[Service]
Type=idle
-Environment=DISPLAY=:0
+Environment="QT_QPA_PLATFORM=wayland"
+Environment="XDG_RUNTIME_DIR=/run/user/1000"

[DenkyTuna]

I have the exact same problem with my RPi 3b+. linuxfb worked for me.
Used qlcplus_raspios_bookworm_20240907.

After changing platform, do

Code: Select all

$ sudo service qlcplus stop

Then

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$ sudo service qlcplus start

By this GUI successfully started.

I just tested the new image and got this:

pi@qlcplus:~ $ sudo qlcplus service status
qt.qpa.xcb: could not connect to display
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, xcb.

Aborted

hdmi_force_hotplug=1 does not seem to work in bookworm

as soon as I plug in a monitor it continues to start

[markzvo]

I have the exact same problem with my RPi 3b+. linuxfb worked for me.
Used qlcplus_raspios_bookworm_20240907.

The latest versions of QLC+ should have display detection. See here:
https://github.com/mcallegari/qlcplus/b ... s-start.sh

Check your startup script above to see if that logic is present (run sudo nano /usr/sbin/qlcplus-start.sh)

The only issue I have seen is that even though QLC+ will start headless *and* with a monitor with this logic, there is no GUI when starting headless, which causes a problem if you have functions mapped in the virtual console to keyboard presses (no GUI is present to "capture" the keypresses).