qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.

JKSH

@CuriousPan said in qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.:

Features used by QPA backends:
...
  xkbcommon .............................. no
  X11 specific:
    XLib ................................. yes
    XCB Xlib ............................. no
    EGL on X11 ........................... yes
    xkbcommon-x11 ........................ no
...
QPA backends:
...
  XCB:
    Using system-provided xcb-xinput ..... no
    GL integrations:
      GLX Plugin ......................... no
        XCB GLX .......................... no
      EGL-X11 Plugin ..................... yes

You need "yes" on all of these. "no" means you were missing the dependencies.

You should:

Clean out your build tree (i.e. delete all files that were not part of the original source code)
Install all the dependencies for Ubuntu at https://wiki.qt.io/Building_Qt_5_from_Git (pay particular attention to the "Libxcb" section)
Run configure again. Make sure you get "yes" on all of the above.
Run make to build Qt.

You should now have all the XCB-related libraries.

CuriousPan

@JKSH, thank you for response. I will try mentioned steps. But is it relevant for Qt6 too?

JKSH

@CuriousPan said in qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.:

@JKSH, thank you for response. I will try mentioned steps. But is it relevant for Qt6 too?

You're welcome.

Yes, I believe the XCB requirements for Qt 5 and Qt 6 are very similar (or even identical)

CuriousPan

@JKSH, thank you for your help. Your advice solved my problems. Steps from the link installed dependencies properly and now everything runs perfectly.

Zayn

Dears,
Could you please help? I'm trying to open turtlesim on my Unbutu 20.04 that I installed on my windows10 computer from the Microsoft store and that is what I'm getting

rosrun turtlesim turtlesim_node
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, xcb.

Aborted (core dumped)

JKSH

@Zayn said in qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.:

Unbutu 20.04 that I installed on my windows10 computer from the Microsoft store

The Windows Subsystem for Linux does not support GUIs. So you cannot run any apps that need XCB.

You have 2 options:

Install a full Ubuntu desktop instead, either on a physical machine or a virtual machine.
Wait until WSLg is released to the general public: https://devblogs.microsoft.com/commandline/the-initial-preview-of-gui-app-support-is-now-available-for-the-windows-subsystem-for-linux-2/

Zayn

@JKSH Many thanks

corebonts

@Zayn
I had the same problem running p4merge on WSL2

First, what you have to do is to install an xserver on windows, like VcXSrv.
Then create a shortcut for the xserver (optional)

"C:\Program Files\VcXsrv\vcxsrv.exe" :0 -ac -terminate -lesspointer -multiwindow -clipboard -wgl -dpi auto

Then in Ubuntu set the xserver display in ~/.bashrc

export DISPLAY=$(ip route | awk '{print $3; exit}'):0
export LIBGL_ALWAYS_INDIRECT=1
export XCURSOR_SIZE=16

Then install the xcb dependency (found at https://wiki.qt.io/Building_Qt_5_from_Git )

sudo apt-get install '^libxcb.*-dev' libx11-xcb-dev libglu1-mesa-dev libxrender-dev libxi-dev libxkbcommon-dev libxkbcommon-x11-dev

Maybe from the last not everything is really needed, but after that it worked for me.

homer9

@corebonts Thanks ! That's solves the issue

JKSH

@homer9 said in qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.:

@corebonts Thanks ! That's solves the issue

The workaround posted by @corebonts should no longer be needed. WSL2 now supports GUIs out-of-the-box: https://learn.microsoft.com/en-us/windows/wsl/tutorials/gui-apps

NicolasZ

@corebonts thx for your solution, solved for me now

mannan_khan

@corebonts Thanks a lot brother it worked for me.

Anuj Srivastava

Thanks corebonts the solution to install '^libxcb' worked for me my application is running smoothly in ubuntu