4.2: Crash (or not?) launching dark themed Qube Manager

Searching through the forum for past advice and experimenting locally I’ve figured out I can launch Qube Manager with a dark theme in 4.2/XFCE in two steps:

# Step 1: Make step 2 work
$ sudo qubes-dom0-update qt5-qtstyleplugins
# ...

# Step 2: Inherit my XFCE theme
# (E.g. System Settings -> Appearance -> Style = Adwaita-dark)
$ QT_QPA_PLATFORMTHEME=gtk2 qubes-qube-manager
# Success -- pleasantly dark Qube Manager.
# (Env assignment eventually to be appended to /etc/environment)

Everything seems great, except for a worrying error message to the terminal:

Cannot mix incompatible Qt library (5.15.5) with this library (5.15.10)

I would have expected such an error to be unrecoverable- but it doesn’t seem to be? Qube Manager appears to be functioning. Yet it makes me anxious, I want a rock solid Qube Manager.

Any intuition about whether I need to worry about this error in this tool and this context?

Any intuition about how I might resolve the incompatibility?

I assume it’s that one or more libraries in qt5-qtstyleplugins have been built against a different version of Qt than that of some underlying library/ies of qubes-qube-manager, and maybe I just need to reinstall a package or two, but I’m not clear on a straightforward way to dig deeper from here.

$ rpm -ql qt5-qtstyleplugins

Strange… :no_mouth: Have 4.2 and did the changes the way you posted… No issues yet! It’s working on a Lenovo P50 and a Nitro-PC

Thanks. Just to verify, when you launch Qube Manager from the terminal you see nothing on stderr?

QT_QPA_PLATFORMTHEME=gtk2 qubes-qube-manager

Ahhh okay - then I’m getting your mentioned error message

Cannot mix incompatible Qt library (5.15.5) with this library (5.15.10)

But never starts the manager that way… Always starting it with a left click on the blue “Qube Domains” qube in the info bar.

But some more infos: There were different ways to get a dark qubes manager. For 4.2 they were coming up with this:

cat "$HOME/.config/'The Qubes Project'/qubes-qube-manager.conf"

but it never changed anything on my 4.2, and so I still followed the changes I did on 4.1 which were those:

Source & Info: https://github.com/QubesOS/qubes-issues/issues/7389

Install the package qt5-qtstyleplugins with:

sudo qubes-dom0-update qt5-qtstyleplugins

then insert in /etc/environment:


in dom0 terminal do:



finally you can check, if all changes were set & working:

[TheGardner@dom0]$ cat /etc/environment

[TheGardner@dom0]$ echo $QT_QPA_PLATFORMTHEME

[TheGardner@dom0]$ sudo dnf info qt5-qtstyleplugins
Qubes OS Repository for Dom0                                                     1.9 MB/s | 3.0 kB     00:00
Installed Packages
Name         : qt5-qtstyleplugins
Version      : 5.0.0
Release      : 39.fc32
Architecture : x86_64
Size         : 1.2 M
Source       : qt5-qtstyleplugins-5.0.0-39.fc32.src.rpm
Repository   : @System
 From repo    : qubes-dom0-cached
Summary      : Classic Qt widget styles
URL          : https://github.com/qtproject/qtstyleplugins
License      : LGPLv2 or GPLv2
Description  : Classic Qt widget styles, including cleanlooks, motif, plastique, qgtk.
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Thanks for checking. I bet this same error is emitted also when you launch through the GUI, it’s just you don’t see it because there’s no terminal to log it to. (qubes-qube-manager picks up QT_QPA_PLATFORMTHEME=gtk2 by way of /etc/environment in that case.)

I think the takeaway here is the error, though sounding dire, is not too important. :+1: