Missing libraries what Qt plugin is built against

nikkej · August 28, 2026, 10:51am

I use KDE plasma on wayland. If I try to launch e.g. previously working dolphin now, I get a buns of notifications:

dolphin
qt.qpa.xcb: could not connect to display
qt.qpa.plugin: From 6.5.0, xcb-cursor0 or libxcb-cursor0 is needed to load the Qt xcb platform plugin.
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, vkkhrdisplay, vnc, wayland-brcm, wayland-egl, wayland, xcb.

Aborted                    (core dumped) dolphin

What I can try?

hcvv · August 28, 2026, 12:35pm

And what is the difference between “previously” and now?
Did you apply an update? Other actions? Or happens this just out of the blue?

nikkej · August 28, 2026, 12:53pm

Oh, I applied multiple distrbution updates in between and unfortunently I don’t know which of them caused dolphin to fail. Currently I run TW 20260826

malcolmlewis · August 28, 2026, 12:56pm

@nikkej what does the output from zypper lr -d show, likewise zypper se -si dolphin

knurpht · August 28, 2026, 12:57pm

Start comparing this with your own:

libxcb-res0-1.17.0-2.7.x86_64
libxcb-randr0-1.17.0-2.7.x86_64
libxcb-composite0-1.17.0-2.7.x86_64
libxcb-keysyms1-0.4.1-1.11.x86_64
libxcb-shm0-1.17.0-2.7.x86_64
libxcb-dri2-0-1.17.0-2.7.x86_64
libxcb-dpms0-1.17.0-2.7.x86_64
libxcb-xkb1-1.17.0-2.7.x86_64
libxcb-util1-0.4.1-1.10.x86_64
libxcb-xv0-1.17.0-2.7.x86_64
libxcb-render0-1.17.0-2.7.x86_64
libxcb-cursor0-0.1.6-1.5.x86_64
libxcb-shape0-1.17.0-2.7.x86_64
libxcb-xf86dri0-1.17.0-2.7.x86_64
libxcb-record0-1.17.0-2.7.x86_64
libX11-xcb1-1.8.13-1.5.x86_64
libxcb1-1.17.0-2.7.x86_64
libxcb-image0-0.4.1-1.12.x86_64
libxcb-present0-1.17.0-2.7.x86_64
libxcb-xinerama0-1.17.0-2.7.x86_64
libxcb-dri3-0-1.17.0-2.7.x86_64
libxcb-xtest0-1.17.0-2.7.x86_64
libxcb-xvmc0-1.17.0-2.7.x86_64
libxcb-damage0-1.17.0-2.7.x86_64
libxcb-xinput0-1.17.0-2.7.x86_64
libxcb-glx0-1.17.0-2.7.x86_64
libxcb-render-util0-0.3.10-1.11.x86_64
libxcb-dbe0-1.17.0-2.7.x86_64
libxcb-sync1-1.17.0-2.7.x86_64
libxcb-screensaver0-1.17.0-2.7.x86_64
libxcb-devel-1.17.0-2.7.x86_64
libxcb-xfixes0-1.17.0-2.7.x86_64
libxcb-icccm4-0.4.2-1.10.x86_64

nikkej · August 28, 2026, 1:46pm

My zypper lr -d says:

# | Alias        | Name                       | Enabled | GPG Check | Refresh | Keep | Priority | Type   | URI                                                                      | Service
--+--------------+----------------------------+---------+-----------+---------+------+----------+--------+--------------------------------------------------------------------------+--------
1 | graphics     | graphics                   | Yes     | (r ) Yes  | Yes     | Yes  |  100     | rpm-md | https://download.opensuse.org/repositories/graphics/openSUSE_Tumbleweed/ |
2 | packman      | packman                    | Yes     | (r ) Yes  | Yes     | Yes  |   90     | rpm-md | https://ftp.gwdg.de/pub/linux/misc/packman/suse/openSUSE_Tumbleweed/     |
3 | repo-debug   | openSUSE-Tumbleweed-Debug  | No      | ----      | ----    | Yes  |   99     | N/A    | http://download.opensuse.org/debug/tumbleweed/repo/oss/                  |
4 | repo-non-oss | repo-non-oss               | Yes     | (r ) Yes  | Yes     | -    |   99     | rpm-md | http://download.opensuse.org/tumbleweed/repo/non-oss                     |
5 | repo-oss     | repo-oss                   | Yes     | (r ) Yes  | Yes     | -    |   99     | rpm-md | http://download.opensuse.org/tumbleweed/repo/oss/                        |
6 | repo-source  | openSUSE-Tumbleweed-Source | No      | ----      | ----    | Yes  |   99     | N/A    | http://download.opensuse.org/source/tumbleweed/repo/oss/                 |
7 | repo-update  | repo-update                | Yes     | (r ) Yes  | Yes     | -    |   99     | rpm-md | http://download.opensuse.org/update/tumbleweed/                          |

And my zypper se -si dolphin say:

Loading repository data...
Reading installed packages...

S  | Name           | Type    | Version     | Arch   | Repository
---+----------------+---------+-------------+--------+-----------
i+ | dolphin        | package | 26.08.0-1.1 | x86_64 | repo-oss
i  | dolphin-part   | package | 26.08.0-1.1 | x86_64 | repo-oss
i  | libdolphinvcs6 | package | 26.08.0-1.1 | x86_64 | repo-oss

nikkej · August 28, 2026, 1:56pm

Ööh , what were command and exact options your list you built?

rrahl0 · August 28, 2026, 1:58pm

the command is rpm -qa *xcb*

nikkej · August 28, 2026, 2:37pm

Thanks Richard

nikkej · August 30, 2026, 9:23am

Ok.I filed a bug report https://bugzilla.opensuse.org/show_bug.cgi?id=1277448
For example I have xcb-util-cursor-devel installed while at the same time xcb-util-cursor does not even exist

shundhammer · August 30, 2026, 9:42am

“Could not connect to display” and then no “:0” means that $DISPLAY is not set, i.e. it’s running in a Wayland environment.

But the Qt platform plugins are all in the same package: libQt6Gui6

[sh @ meteor] ...qt6/plugins/platforms 12 % ls -l
total 1088
-rwxr-xr-x 1 root root  18928 Aug 14 10:27 libqeglfs.so
-rwxr-xr-x 1 root root 442992 Aug 14 10:27 libqlinuxfb.so
-rwxr-xr-x 1 root root  43504 Aug 14 10:27 libqminimalegl.so
-rwxr-xr-x 1 root root  39408 Aug 14 10:27 libqminimal.so
-rwxr-xr-x 1 root root 125424 Aug 14 10:27 libqoffscreen.so
-rwxr-xr-x 1 root root 270200 Aug 14 10:27 libqvkkhrdisplay.so
-rwxr-xr-x 1 root root 122224 Aug 14 10:27 libqvnc.so
-rwxr-xr-x 1 root root  18928 Aug 14 10:27 libqwayland.so
-rwxr-xr-x 1 root root  18928 Aug 14 10:27 libqxcb.so
[sh @ meteor] ...qt6/plugins/platforms 13 % rpm -qf libqxcb.so 
libQt6Gui6-6.11.1-2.0.2.1.sr20260802.x86_64
[sh @ meteor] ...qt6/plugins/platforms 14 % rpm -qf libqwayland.so 
libQt6Gui6-6.11.1-2.0.2.1.sr20260802.x86_64
[sh @ meteor] ...qt6/plugins/platforms 15 % rpm -ql libQt6Gui6 | grep platforms
/usr/lib64/qt6/plugins/platforms
/usr/lib64/qt6/plugins/platforms/libqeglfs.so
/usr/lib64/qt6/plugins/platforms/libqlinuxfb.so
/usr/lib64/qt6/plugins/platforms/libqminimal.so
/usr/lib64/qt6/plugins/platforms/libqminimalegl.so
/usr/lib64/qt6/plugins/platforms/libqoffscreen.so
/usr/lib64/qt6/plugins/platforms/libqvkkhrdisplay.so
/usr/lib64/qt6/plugins/platforms/libqvnc.so
/usr/lib64/qt6/plugins/platforms/libqwayland.so
/usr/lib64/qt6/plugins/platforms/libqxcb.so

So please check if that package is installed (probably it’s not):

[sh @ meteor] ...qt6/plugins/platforms 16 % zypper search -i libQt6Gui6
Loading repository data...
Reading installed packages...

S  | Name       | Summary                    | Type
---+------------+----------------------------+--------
i+ | libQt6Gui6 | Qt 6 GUI related libraries | package

shundhammer · August 30, 2026, 9:49am

Also check if you get any errors about missing shared libraries from

ldd /usr/lib64/qt6/plugins/platforms/libqxcb.so

nikkej · August 30, 2026, 11:11am

Thanks Stefan. libQt6Gui6 is (and was) installed. Also, no build time shared library errors for libqxcb.so

nikkej · August 30, 2026, 11:54am

Stefan et.all, what do you think about this:

# zypper in xcb-util-cursor
Loading repository data...
Reading installed packages...
Package 'xcb-util-cursor' not found.
Resolving package dependencies...
Nothing to do.
# zypper se -s xcb-util-cursor
Loading repository data...
Reading installed packages...

S  | Name                        | Type    | Version   | Arch   | Repository
---+-----------------------------+---------+-----------+--------+-----------
i+ | xcb-util-cursor-devel       | package | 0.1.6-1.5 | x86_64 | repo-oss
   | xcb-util-cursor-devel-32bit | package | 0.1.6-1.5 | x86_64 | repo-oss

And yes, all repos are refreshed

hui · August 30, 2026, 11:57am

xcb-util-cursor is the source package fpr libxcb-cursor0

shundhammer · August 30, 2026, 12:29pm

RPM auto-generates provides and requires for shared libs. In this case:

sh@meteor:~> zypper info --requires libQt6Gui6 | grep cursor
    libxcb-cursor.so.0()(64bit)
sh@meteor:~> zypper search --provides libxcb-cursor.so.0
Loading repository data...
Reading installed packages...

S  | Name                 | Summary                              | Type
---+----------------------+--------------------------------------+--------
i+ | libxcb-cursor0       | XCB cursor library (libxcursor port) | package
   | libxcb-cursor0-32bit | XCB cursor library (libxcursor port) | package

So libQt6Gui6 requires “libxcb-cursor.so.0()(64bit)” which is provided by package libxcb-cursor0.

Still, the elephant in the room is why Qt wants do execute Dolphin in X11 (xcb) mode (i.e. via XWayland) and not in Wayland mode, i.e. as a native Wayland application. Qt can do both, so why does it choose xcb and not Wayland?

nikkej · August 30, 2026, 12:49pm

Stefan,there is reason for that. While wayland is native,local install I run X11apps remotely over ssh

nikkej · August 30, 2026, 1:14pm

And what do you think about this:

# zypper se -s libxcb-cursor
Loading repository data...
Reading installed packages...

S  | Name                 | Type    | Version   | Arch   | Repository
---+----------------------+---------+-----------+--------+-----------
i  | libxcb-cursor0       | package | 0.1.6-1.5 | x86_64 | repo-oss
   | libxcb-cursor0-32bit | package | 0.1.6-1.5 | x86_64 | repo-oss


# locate libxcb-cursor
/usr/lib64/libxcb-cursor.so.0
/usr/lib64/libxcb-cursor.so.0.0.0

shundhammer · August 30, 2026, 1:20pm

So you are trying to start Dolphin remotely via remote X over ssh? That’s a completely different ballgame. You should have mentioned it from the very start!

In that case, AFAICS most of those Qt warnings are just a red herring - a garbage message telling you to reinstall the application (which is complete BS on the level of “do a factory reset” in Android forums) when the only meaningful part of the message is just the “Can’t open display” part. And then the empty display name becomes the crucial part.

So I hope that the receiving end has an X server running, and you did start the ssh session with ssh -Xor ssh -Y, and / or X11 forwarding is otherwise enabled where needed?

shundhammer · August 30, 2026, 1:22pm

BTW this is why my Myrlyn and my QDirStat suppress this message and replace it with something less misleading:

github.com/shundhammer/qdirstat

src/Logger.cpp

master


      
          if ( msg.contains( "Could not connect to display" ) ||
               msg.contains( "failed to start because no Qt platform plugin" ) )
          {
              if ( msg.contains( "Reinstalling the application may fix this problem" ) )
              {
                  // Suppress this new message which is complete and utter garbage:
                  //
                  // "This application failed to start because no Qt platform
                  // plugin could be initialized. Reinstalling the application
                  // may fix this problem.
                  //
                  // Available platform plugins are: wayland-org.kde.kwin.qpa,
                  // eglfs, linuxfb, minimal, minimalegl, offscreen, vnc,
                  // wayland-egl, wayland, wayland-xcomposite-egl,
                  // wayland-xcomposite-glx, xcb."
                  //
                  // Seriously, who comes up with ■■■■■■■■ like this?
                  //
                  // Anybody who thinks that this might help a user does not have
                  // the first clue about user interaction. This only confuses

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