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

[mywings19]

hi,
I'm facing similar issue.could you give me some suggestion?
my QT version is:Qt Creator 8.0.1 based on Qt 6.3.1

the error message:
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "/home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms" 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: linuxfb, minimal, offscreen, vnc, eglfs, minimalegl, vkkhrdisplay, wayland-egl, wayland, xcb.

Then I've set 'export QT_DEBUG_PLUGINS=1'
but there's no extra error message,qtcreator is running normally

And I've run 'ldd libqxcb.so',result is

        linux-vdso.so.1 (0x00007ffcdb970000)
        libQt6XcbQpa.so.6 => /home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms/./../../lib/libQt6XcbQpa.so.6 (0x00007f02bc4a5000)
        libxkbcommon-x11.so.0 => /lib/x86_64-linux-gnu/libxkbcommon-x11.so.0 (0x00007f02bc476000)
        libxkbcommon.so.0 => /lib/x86_64-linux-gnu/libxkbcommon.so.0 (0x00007f02bc434000)
        libxcb-icccm.so.4 => /lib/x86_64-linux-gnu/libxcb-icccm.so.4 (0x00007f02bc42d000)
        libxcb-image.so.0 => /lib/x86_64-linux-gnu/libxcb-image.so.0 (0x00007f02bc427000)
        libxcb-keysyms.so.1 => /lib/x86_64-linux-gnu/libxcb-keysyms.so.1 (0x00007f02bc422000)
        libxcb-randr.so.0 => /lib/x86_64-linux-gnu/libxcb-randr.so.0 (0x00007f02bc40e000)
        libxcb-render-util.so.0 => /lib/x86_64-linux-gnu/libxcb-render-util.so.0 (0x00007f02bc407000)
        libxcb-shm.so.0 => /lib/x86_64-linux-gnu/libxcb-shm.so.0 (0x00007f02bc402000)
        libxcb-sync.so.1 => /lib/x86_64-linux-gnu/libxcb-sync.so.1 (0x00007f02bc3f8000)
        libxcb-xfixes.so.0 => /lib/x86_64-linux-gnu/libxcb-xfixes.so.0 (0x00007f02bc3ee000)
        libxcb-render.so.0 => /lib/x86_64-linux-gnu/libxcb-render.so.0 (0x00007f02bc3df000)
        libxcb-shape.so.0 => /lib/x86_64-linux-gnu/libxcb-shape.so.0 (0x00007f02bc3d8000)
        libxcb-xkb.so.1 => /lib/x86_64-linux-gnu/libxcb-xkb.so.1 (0x00007f02bc3ba000)
        libxcb.so.1 => /lib/x86_64-linux-gnu/libxcb.so.1 (0x00007f02bc390000)
        libQt6OpenGL.so.6 => /home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms/./../../lib/libQt6OpenGL.so.6 (0x00007f02bc2ee000)
        libQt6Gui.so.6 => /home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms/./../../lib/libQt6Gui.so.6 (0x00007f02bb96b000)
        libGL.so.1 => /lib/x86_64-linux-gnu/libGL.so.1 (0x00007f02bb8d7000)
        libQt6Core.so.6 => /home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms/./../../lib/libQt6Core.so.6 (0x00007f02bb272000)
        libX11-xcb.so.1 => /lib/x86_64-linux-gnu/libX11-xcb.so.1 (0x00007f02bb26d000)
        libX11.so.6 => /lib/x86_64-linux-gnu/libX11.so.6 (0x00007f02bb12c000)
        libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f02bb127000)
        libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f02bb106000)
        libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f02baf82000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f02badfd000)
        libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f02bade3000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f02bac22000)
        libglib-2.0.so.0 => /lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007f02bab03000)
        libgthread-2.0.so.0 => /lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007f02baafe000)
        libxcb-util.so.0 => /lib/x86_64-linux-gnu/libxcb-util.so.0 (0x00007f02baaf2000)
        libXau.so.6 => /lib/x86_64-linux-gnu/libXau.so.6 (0x00007f02baaed000)
        libXdmcp.so.6 => /lib/x86_64-linux-gnu/libXdmcp.so.6 (0x00007f02baae5000)
        libEGL.so.1 => /lib/x86_64-linux-gnu/libEGL.so.1 (0x00007f02baad0000)
        libfontconfig.so.1 => /lib/x86_64-linux-gnu/libfontconfig.so.1 (0x00007f02baa8a000)
        libQt6DBus.so.6 => /home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms/./../../lib/libQt6DBus.so.6 (0x00007f02ba9b8000)
        libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f02ba99b000)
        libfreetype.so.6 => /lib/x86_64-linux-gnu/libfreetype.so.6 (0x00007f02ba8df000)
        libGLX.so.0 => /lib/x86_64-linux-gnu/libGLX.so.0 (0x00007f02ba8ab000)
        libGLdispatch.so.0 => /lib/x86_64-linux-gnu/libGLdispatch.so.0 (0x00007f02ba7ee000)
        libicui18n.so.56 => /home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms/./../../lib/libicui18n.so.56 (0x00007f02ba353000)
        libicuuc.so.56 => /home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms/./../../lib/libicuuc.so.56 (0x00007f02b9f9b000)
        libicudata.so.56 => /home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms/./../../lib/libicudata.so.56 (0x00007f02b85b8000)
        librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f02b85ae000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f02bc55d000)
        libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007f02b853a000)
        libbsd.so.0 => /lib/x86_64-linux-gnu/libbsd.so.0 (0x00007f02b8520000)
        libexpat.so.1 => /lib/x86_64-linux-gnu/libexpat.so.1 (0x00007f02b84e1000)
        libuuid.so.1 => /lib/x86_64-linux-gnu/libuuid.so.1 (0x00007f02b84d8000)
        libdbus-1.so.3 => /lib/x86_64-linux-gnu/libdbus-1.so.3 (0x00007f02b8485000)
        libpng16.so.16 => /lib/x86_64-linux-gnu/libpng16.so.16 (0x00007f02b844c000)
        libXext.so.6 => /lib/x86_64-linux-gnu/libXext.so.6 (0x00007f02b8437000)
        libsystemd.so.0 => /lib/x86_64-linux-gnu/libsystemd.so.0 (0x00007f02b8394000)
        liblzma.so.5 => /lib/x86_64-linux-gnu/liblzma.so.5 (0x00007f02b836c000)
        liblz4.so.1 => /lib/x86_64-linux-gnu/liblz4.so.1 (0x00007f02b834d000)
        libgcrypt.so.20 => /lib/x86_64-linux-gnu/libgcrypt.so.20 (0x00007f02b8228000)
        libgpg-error.so.0 => /lib/x86_64-linux-gnu/libgpg-error.so.0 (0x00007f02b8205000)

what to do next?thank you!

[JonB]

@mywings19 said in qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.:

Then I've set 'export QT_DEBUG_PLUGINS=1'
but there's no extra error message,qtcreator is running normally

Have you actually run whatever executable raises the error (Qt Creator itself?? Your application?) from the shell where you set this environment variable, like all the posts tell you to? Because if so you should get a whole bunch of diagnostic output lines....

[mywings19]

@JonB

sugon@EC:~$ cat ~/.bashrc
# ~/.bashrc: executed by bash(1) for non-login shells.
# see /usr/share/doc/bash/examples/startup-files (in the package bash-doc)
# for examples

# If not running interactively, don't do anything
case $- in
    *i*) ;;
      *) return;;
esac

# don't put duplicate lines or lines starting with space in the history.
# See bash(1) for more options
HISTCONTROL=ignoreboth

# append to the history file, don't overwrite it
shopt -s histappend

# for setting history length see HISTSIZE and HISTFILESIZE in bash(1)
HISTSIZE=1000
HISTFILESIZE=2000

# check the window size after each command and, if necessary,
# update the values of LINES and COLUMNS.
shopt -s checkwinsize

# If set, the pattern "**" used in a pathname expansion context will
# match all files and zero or more directories and subdirectories.
#shopt -s globstar

# make less more friendly for non-text input files, see lesspipe(1)
#[ -x /usr/bin/lesspipe ] && eval "$(SHELL=/bin/sh lesspipe)"

# set variable identifying the chroot you work in (used in the prompt below)
if [ -z "${debian_chroot:-}" ] && [ -r /etc/debian_chroot ]; then
    debian_chroot=$(cat /etc/debian_chroot)
fi

# set a fancy prompt (non-color, unless we know we "want" color)
case "$TERM" in
    xterm-color|*-256color) color_prompt=yes;;
esac

# uncomment for a colored prompt, if the terminal has the capability; turned
# off by default to not distract the user: the focus in a terminal window
# should be on the output of commands, not on the prompt
#force_color_prompt=yes

if [ -n "$force_color_prompt" ]; then
    if [ -x /usr/bin/tput ] && tput setaf 1 >&/dev/null; then
        # We have color support; assume it's compliant with Ecma-48
        # (ISO/IEC-6429). (Lack of such support is extremely rare, and such
        # a case would tend to support setf rather than setaf.)
        color_prompt=yes
    else
        color_prompt=
    fi
fi

if [ "$color_prompt" = yes ]; then
    PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '
else
    PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
fi
unset color_prompt force_color_prompt

# If this is an xterm set the title to user@host:dir
case "$TERM" in
xterm*|rxvt*)
    PS1="\[\e]0;${debian_chroot:+($debian_chroot)}\u@\h: \w\a\]$PS1"
    ;;
*)
    ;;
esac

# enable color support of ls and also add handy aliases
if [ -x /usr/bin/dircolors ]; then
    test -r ~/.dircolors && eval "$(dircolors -b ~/.dircolors)" || eval "$(dircolors -b)"
    alias ls='ls --color=auto'
    #alias dir='dir --color=auto'
    #alias vdir='vdir --color=auto'

    #alias grep='grep --color=auto'
    #alias fgrep='fgrep --color=auto'
    #alias egrep='egrep --color=auto'
fi

# colored GCC warnings and errors
#export GCC_COLORS='error=01;31:warning=01;35:note=01;36:caret=01;32:locus=01:quote=01'

# some more ls aliases
#alias ll='ls -l'
#alias la='ls -A'
#alias l='ls -CF'

# Alias definitions.
# You may want to put all your additions into a separate file like
# ~/.bash_aliases, instead of adding them here directly.
# See /usr/share/doc/bash-doc/examples in the bash-doc package.

if [ -f ~/.bash_aliases ]; then
    . ~/.bash_aliases
fi

# enable programmable completion features (you don't need to enable
# this, if it's already enabled in /etc/bash.bashrc and /etc/profile
# sources /etc/bash.bashrc).
if ! shopt -oq posix; then
  if [ -f /usr/share/bash-completion/bash_completion ]; then
    . /usr/share/bash-completion/bash_completion
  elif [ -f /etc/bash_completion ]; then
    . /etc/bash_completion
  fi
fi
# Set LS_COLORS environment by Deepin
if [[ ("$TERM" = *256color || "$TERM" = screen* || "$TERM" = xterm* ) && -f /etc/lscolor-256color ]]; then
    eval $(dircolors -b /etc/lscolor-256color)
else
    eval $(dircolors)
fi

export QT_DEBUG_PLUGINS=1
export QT_QPA_PLATFORM_PLUGIN_PATH=/home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms
sugon@EC:~$ source ~/.bashrc
sugon@EC:~$ ~/Software/qtcreator8.0.1/bin/qtcreator
sugon@EC:~$ ~/QtProject/build-Test-Qt_6_3_1_in_PATH_Qt6_3_1-Debug/Test
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "/home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms" 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: linuxfb, minimal, offscreen, vnc, eglfs, minimalegl, vkkhrdisplay, wayland-egl, wayland, xcb.

Aborded
sugon@EC:~$ ldd ~/Software/qtcreator8.0.1/lib/Qt/plugins/platforms/libqxcb.so 
        linux-vdso.so.1 (0x00007ffeb7df5000)
        libQt6XcbQpa.so.6 => /home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms/../../lib/libQt6XcbQpa.so.6 (0x00007fd7162df000)
        libxkbcommon-x11.so.0 => /lib/x86_64-linux-gnu/libxkbcommon-x11.so.0 (0x00007fd7162b0000)
        libxkbcommon.so.0 => /lib/x86_64-linux-gnu/libxkbcommon.so.0 (0x00007fd71626e000)
        libxcb-icccm.so.4 => /lib/x86_64-linux-gnu/libxcb-icccm.so.4 (0x00007fd716267000)
        libxcb-image.so.0 => /lib/x86_64-linux-gnu/libxcb-image.so.0 (0x00007fd716261000)
        libxcb-keysyms.so.1 => /lib/x86_64-linux-gnu/libxcb-keysyms.so.1 (0x00007fd71625c000)
        libxcb-randr.so.0 => /lib/x86_64-linux-gnu/libxcb-randr.so.0 (0x00007fd716248000)
        libxcb-render-util.so.0 => /lib/x86_64-linux-gnu/libxcb-render-util.so.0 (0x00007fd716241000)
        libxcb-shm.so.0 => /lib/x86_64-linux-gnu/libxcb-shm.so.0 (0x00007fd71623c000)
        libxcb-sync.so.1 => /lib/x86_64-linux-gnu/libxcb-sync.so.1 (0x00007fd716232000)
        libxcb-xfixes.so.0 => /lib/x86_64-linux-gnu/libxcb-xfixes.so.0 (0x00007fd716228000)
        libxcb-render.so.0 => /lib/x86_64-linux-gnu/libxcb-render.so.0 (0x00007fd716219000)
        libxcb-shape.so.0 => /lib/x86_64-linux-gnu/libxcb-shape.so.0 (0x00007fd716212000)
        libxcb-xkb.so.1 => /lib/x86_64-linux-gnu/libxcb-xkb.so.1 (0x00007fd7161f4000)
        libxcb.so.1 => /lib/x86_64-linux-gnu/libxcb.so.1 (0x00007fd7161ca000)
        libQt6OpenGL.so.6 => /home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms/../../lib/libQt6OpenGL.so.6 (0x00007fd716128000)
        libQt6Gui.so.6 => /home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms/../../lib/libQt6Gui.so.6 (0x00007fd7157a5000)
        libGL.so.1 => /lib/x86_64-linux-gnu/libGL.so.1 (0x00007fd715711000)
        libQt6Core.so.6 => /home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms/../../lib/libQt6Core.so.6 (0x00007fd7150ac000)
        libX11-xcb.so.1 => /lib/x86_64-linux-gnu/libX11-xcb.so.1 (0x00007fd7150a7000)
        libX11.so.6 => /lib/x86_64-linux-gnu/libX11.so.6 (0x00007fd714f66000)
        libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fd714f61000)
        libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fd714f40000)
        libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007fd714dbc000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fd714c37000)
        libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fd714c1d000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fd714a5c000)
        libglib-2.0.so.0 => /lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007fd71493d000)
        libgthread-2.0.so.0 => /lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007fd714938000)
        libxcb-util.so.0 => /lib/x86_64-linux-gnu/libxcb-util.so.0 (0x00007fd71492c000)
        libXau.so.6 => /lib/x86_64-linux-gnu/libXau.so.6 (0x00007fd714927000)
        libXdmcp.so.6 => /lib/x86_64-linux-gnu/libXdmcp.so.6 (0x00007fd71491f000)
        libEGL.so.1 => /lib/x86_64-linux-gnu/libEGL.so.1 (0x00007fd71490a000)
        libfontconfig.so.1 => /lib/x86_64-linux-gnu/libfontconfig.so.1 (0x00007fd7148c4000)
        libQt6DBus.so.6 => /home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms/../../lib/libQt6DBus.so.6 (0x00007fd7147f2000)
        libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007fd7147d5000)
        libfreetype.so.6 => /lib/x86_64-linux-gnu/libfreetype.so.6 (0x00007fd714719000)
        libGLX.so.0 => /lib/x86_64-linux-gnu/libGLX.so.0 (0x00007fd7146e5000)
        libGLdispatch.so.0 => /lib/x86_64-linux-gnu/libGLdispatch.so.0 (0x00007fd714628000)
        libicui18n.so.56 => /home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms/../../lib/libicui18n.so.56 (0x00007fd71418d000)
        libicuuc.so.56 => /home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms/../../lib/libicuuc.so.56 (0x00007fd713dd5000)
        libicudata.so.56 => /home/sugon/Software/qtcreator8.0.1/lib/Qt/plugins/platforms/../../lib/libicudata.so.56 (0x00007fd7123f2000)
        librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007fd7123e8000)
        /lib64/ld-linux-x86-64.so.2 (0x00007fd716397000)
        libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007fd712374000)
        libbsd.so.0 => /lib/x86_64-linux-gnu/libbsd.so.0 (0x00007fd71235a000)
        libexpat.so.1 => /lib/x86_64-linux-gnu/libexpat.so.1 (0x00007fd71231b000)
        libuuid.so.1 => /lib/x86_64-linux-gnu/libuuid.so.1 (0x00007fd712312000)
        libdbus-1.so.3 => /lib/x86_64-linux-gnu/libdbus-1.so.3 (0x00007fd7122bf000)
        libpng16.so.16 => /lib/x86_64-linux-gnu/libpng16.so.16 (0x00007fd712286000)
        libXext.so.6 => /lib/x86_64-linux-gnu/libXext.so.6 (0x00007fd712271000)
        libsystemd.so.0 => /lib/x86_64-linux-gnu/libsystemd.so.0 (0x00007fd7121ce000)
        liblzma.so.5 => /lib/x86_64-linux-gnu/liblzma.so.5 (0x00007fd7121a6000)
        liblz4.so.1 => /lib/x86_64-linux-gnu/liblz4.so.1 (0x00007fd712187000)
        libgcrypt.so.20 => /lib/x86_64-linux-gnu/libgcrypt.so.20 (0x00007fd712062000)
        libgpg-error.so.0 => /lib/x86_64-linux-gnu/libgpg-error.so.0 (0x00007fd71203f000)
sugon@EC:~$ 

[SGaist]

Hi,

Why are you pointing the plugin path to Qt Creator's installation rather than the Qt version you used to build your application ?

By default you should not even need to use that variable.

[mywings19]

@SGaist
Me?That might be the problem

When I point the Qt plugin path, 'xcb' couldn't be found
sugon@EC:~$ ~/QtProject/build-Test-Qt_6_3_1_in_PATH_Qt6_3_1-Debug/Test
qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in "/home/sugon/Software/Qt6.3.1/plugins/platforms/"
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
Available platform plugins are: linuxfb, minimal, offscreen, vnc.

So shall I reinstall the Qt or add some plugins?
Thank you

[SGaist]

Start your application with the QT_DEBUG_PLUGINS environment variable set to 1 to see why the loading fails.

[mywings19]

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

Start your application with the QT_DEBUG_PLUGINS environment variable set to 1 to see why the loading fails.

I've set the QT_DEBUG_PLUGINS environment variable in the .bashrc file and sourced it. See floor.134
But these is no error message while loading qtcreator.

sugon@EC:~$ echo $QT_DEBUG_PLUGINS
1
sugon@EC:~$

[hskoglund]

Hi, perhaps you are launching Qt Creator by double clicking on it?
If so, instead try starting Qt Creator from the same Terminal window that has QT_DEBUG_PLUGINS set to 1.

[mywings19]

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

Hi, perhaps you are launching Qt Creator by double clicking on it?
If so, instead try starting Qt Creator from the same Terminal window that has QT_DEBUG_PLUGINS set to 1.

Thank you, but I always start qtcreator in terminal. It can be seen in floor.134

sugon@EC:~$ source ~/.bashrc
sugon@EC:~$ ~/Software/qtcreator8.0.1/bin/qtcreator
sugon@EC:~$ ~/QtProject/build-Test-Qt_6_3_1_in_PATH_Qt6_3_1-Debug/Test

There's no error message until I closed the software.

[JonB]

@mywings19 said in qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.:

There's no error message until I closed the software.

In that case when does the message you showed earlier:

qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in "/home/sugon/Software/Qt6.3.1/plugins/platforms/"
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
Available platform plugins are: linuxfb, minimal, offscreen, vnc.

appear? Not until after you close Creator? Interesting.....

[mywings19]

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

@mywings19 said in qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.:

There's no error message until I closed the software.

In that case when does the message you showed earlier:

qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in "/home/sugon/Software/Qt6.3.1/plugins/platforms/"
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
Available platform plugins are: linuxfb, minimal, offscreen, vnc.

appear? Not until after you close Creator? Interesting.....

This 3 line message is showed when I build and run a test project.
I mean after I set QT_DEBUG_PLUGINS to 1, There's no extra error message except this 3 line when I start qtcreator or run project in terminal.

Now, I've uninstall the Qt and qtcreator,then installing by online installer.

[SGaist]

Is that a custom Qt build ? Because from the looks of it, the plugin is indeed not there.

[BenyaminZojaji]

In my case, I just upgrade PyQt5 to PyQt6 and that works.

[GEZawaTT]

@trimixotun this worked!! Thank you so much!

[3mad]

In my case, I had the issue when installing ParaView, things fixed by installing the libxcb-xinput0 package:
sudo apt-get install libxcb-xinput0

Then, things work fine.

[roux.benoit]

Hi,

I know this is an old post, but I have the same issue that comes up when I'm setting some path for the LD_Library_path.

for the context i'm creating a container that run an app with a gui using pyqt5, which works perfectly.

However, I also need to install matlab runtime and after I set up Matlab runtime environement path :

LD_LIBRARY_PATH=/opt/mscr/v912/runtime/glnxa64:/opt/mcr/v912/bin/glnxa64:/opt/mcr/v912/sys/os/glnxa64:/opt/mcr/v912/sys/opengl/lib/glnxa64

the gui stops working and I get the "qt.qpa.plugin ..." error message.

Any thoughts?
Thanks a lot

[SGaist]

@roux-benoit hi,

Check whether there's Qt libraries in your matlab installation.

[phil-lipp]

I hope someone on this forum can help me. I'm trying to use Howdy (https://github.com/boltgolt/howdy), but I get the error described by OP.
I only get the error when I use su -, however when I use plain su (without the -) it works. So I think i somehow messed up the install when I forgot to add the -... how can I fix this?

the error:

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.
``

[JonB]

@phil-lipp
https://forum.qt.io/post/763171 was just asked.

[MarsOnMart]

I had too problems with this file.
It just depends from which shared file left you.
first at all set in the console :

export QT_DEBUG_PLUGINS=1

This will show you in which part it fails, normally is in libqxcb.so,

example:
python main.py

qt.core.plugin.factoryloader: checking directory path "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms" ...
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqwayland-generic.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqwayland-generic.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "wayland"
        ]
    },
    "archlevel": 1,
    "className": "QWaylandIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("wayland")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqminimal.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqminimal.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "minimal"
        ]
    },
    "archlevel": 1,
    "className": "QMinimalIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("minimal")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqeglfs.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqeglfs.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "eglfs"
        ]
    },
    "archlevel": 1,
    "className": "QEglFSIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("eglfs")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqwayland-egl.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqwayland-egl.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "wayland-egl"
        ]
    },
    "archlevel": 1,
    "className": "QWaylandEglPlatformIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("wayland-egl")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqoffscreen.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqoffscreen.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "offscreen"
        ]
    },
    "archlevel": 1,
    "className": "QOffscreenIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("offscreen")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqlinuxfb.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqlinuxfb.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "linuxfb"
        ]
    },
    "archlevel": 1,
    "className": "QLinuxFbIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("linuxfb")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqvnc.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqvnc.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "vnc"
        ]
    },
    "archlevel": 1,
    "className": "QVncIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("vnc")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqvkkhrdisplay.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqvkkhrdisplay.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "vkkhrdisplay"
        ]
    },
    "archlevel": 1,
    "className": "QVkKhrDisplayIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("vkkhrdisplay")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqminimalegl.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqminimalegl.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "minimalegl"
        ]
    },
    "archlevel": 1,
    "className": "QMinimalEglIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("minimalegl")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "xcb"
        ]
    },
    "archlevel": 1,
    "className": "QXcbIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("xcb")
qt.core.plugin.factoryloader: checking directory path "/usr/bin/platforms" ...
qt.core.library: "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so" cannot load: Cannot load library /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so: (libxcb-cursor.so.0: cannot open shared object file: No such file or directory)
qt.core.plugin.loader: QLibraryPrivate::loadPlugin failed on "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so" : "Cannot load library /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so: (libxcb-cursor.so.0: cannot open shared object file: No such file or directory)"
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: wayland, minimal, eglfs, wayland-egl, offscreen, linuxfb, vnc, vkkhrdisplay, minimalegl, xcb.

zsh: IOT instruction  python main.py

And this error occurs when some of the shared libraries are not found.
In my case was the :
"/usr/bin/platforms" ...
qt.core.library: "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so" cannot load: Cannot load library /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so:

== =>(libxcb-cursor.so.0: cannot open shared object file: No such file or directory) <===

qt.core.plugin.loader: QLibraryPrivate::loadPlugin failed on "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so" : "Cannot load library /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so: (libxcb-cursor.so.0: cannot open shared object file: No such file or directory)"
.
This is the shared library that lefts , it could that does not be the only one , so for see better which shared libraries are and which not use the next command :

ldd : /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so

This must show you the next thing :

::
ldd: ./:: No such file or directory
/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so:
        linux-vdso.so.1 (0x00007fff8b5b6000)
        libQt6XcbQpa.so.6 => /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/../../lib/libQt6XcbQpa.so.6 (0x00007febd8bec000)
        libxkbcommon-x11.so.0 => /lib/x86_64-linux-gnu/libxkbcommon-x11.so.0 (0x00007febd8bc3000)
        libxkbcommon.so.0 => /lib/x86_64-linux-gnu/libxkbcommon.so.0 (0x00007febd8b7d000)
        libxcb-cursor.so.0 => not found
        libxcb-icccm.so.4 => /lib/x86_64-linux-gnu/libxcb-icccm.so.4 (0x00007febd8b76000)
        libxcb-image.so.0 => /lib/x86_64-linux-gnu/libxcb-image.so.0 (0x00007febd8b6e000)
        libxcb-keysyms.so.1 => /lib/x86_64-linux-gnu/libxcb-keysyms.so.1 (0x00007febd8800000)
        libxcb-randr.so.0 => /lib/x86_64-linux-gnu/libxcb-randr.so.0 (0x00007febd8b5d000)
        libxcb-render-util.so.0 => /lib/x86_64-linux-gnu/libxcb-render-util.so.0 (0x00007febd8400000)
        libxcb-shm.so.0 => /lib/x86_64-linux-gnu/libxcb-shm.so.0 (0x00007febd8b58000)
        libxcb-sync.so.1 => /lib/x86_64-linux-gnu/libxcb-sync.so.1 (0x00007febd8b50000)
        libxcb-xfixes.so.0 => /lib/x86_64-linux-gnu/libxcb-xfixes.so.0 (0x00007febd8b45000)
        libxcb-render.so.0 => /lib/x86_64-linux-gnu/libxcb-render.so.0 (0x00007febd8b37000)
        libxcb-shape.so.0 => /lib/x86_64-linux-gnu/libxcb-shape.so.0 (0x00007febd8b32000)
        libxcb-xkb.so.1 => /lib/x86_64-linux-gnu/libxcb-xkb.so.1 (0x00007febd8b15000)
        libxcb.so.1 => /lib/x86_64-linux-gnu/libxcb.so.1 (0x00007febd8aeb000)
        libQt6OpenGL.so.6 => /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/../../lib/libQt6OpenGL.so.6 (0x00007febd8a4a000)
        libQt6Gui.so.6 => /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/../../lib/libQt6Gui.so.6 (0x00007febd7a00000)
        libGL.so.1 => /lib/x86_64-linux-gnu/libGL.so.1 (0x00007febd8779000)
        libQt6Core.so.6 => /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/../../lib/libQt6Core.so.6 (0x00007febd7200000)
        libX11-xcb.so.1 => /lib/x86_64-linux-gnu/libX11-xcb.so.1 (0x00007febd8a43000)
        libX11.so.6 => /lib/x86_64-linux-gnu/libX11.so.6 (0x00007febd8637000)
        libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007febd8a3c000)
        libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007febd8a37000)
        libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007febd6e00000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007febd7921000)
        libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007febd8a17000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007febd701f000)
        libxcb-cursor.so.0 => not found
        libglib-2.0.so.0 => /lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007febd6cbd000)
        libgthread-2.0.so.0 => /lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007febd8a10000)
        libxcb-util.so.1 => /lib/x86_64-linux-gnu/libxcb-util.so.1 (0x00007febd8a08000)
        libXau.so.6 => /lib/x86_64-linux-gnu/libXau.so.6 (0x00007febd8a03000)
        libXdmcp.so.6 => /lib/x86_64-linux-gnu/libXdmcp.so.6 (0x00007febd6a00000)
        libEGL.so.1 => /lib/x86_64-linux-gnu/libEGL.so.1 (0x00007febd861f000)
        libfontconfig.so.1 => /lib/x86_64-linux-gnu/libfontconfig.so.1 (0x00007febd78d6000)
        libQt6DBus.so.6 => /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/../../lib/libQt6DBus.so.6 (0x00007febd693b000)
        libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007febd83e1000)
        libfreetype.so.6 => /lib/x86_64-linux-gnu/libfreetype.so.6 (0x00007febd6870000)
        libGLdispatch.so.0 => /lib/x86_64-linux-gnu/libGLdispatch.so.0 (0x00007febd67b7000)
        libGLX.so.0 => /lib/x86_64-linux-gnu/libGLX.so.0 (0x00007febd78a2000)
        libicui18n.so.56 => /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/../../lib/libicui18n.so.56 (0x00007febd6200000)
        libicuuc.so.56 => /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/../../lib/libicuuc.so.56 (0x00007febd5e00000)
        libicudata.so.56 => /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/../../lib/libicudata.so.56 (0x00007febd4400000)
        librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007febd8616000)
        /lib64/ld-linux-x86-64.so.2 (0x00007febd8ca7000)
        libpcre2-8.so.0 => /lib/x86_64-linux-gnu/libpcre2-8.so.0 (0x00007febd6c23000)
        libbsd.so.0 => /lib/x86_64-linux-gnu/libbsd.so.0 (0x00007febd83cb000)
        libexpat.so.1 => /lib/x86_64-linux-gnu/libexpat.so.1 (0x00007febd678c000)
        libdbus-1.so.3 => /lib/x86_64-linux-gnu/libdbus-1.so.3 (0x00007febd6736000)
        libpng16.so.16 => /lib/x86_64-linux-gnu/libpng16.so.16 (0x00007febd6700000)
        libbrotlidec.so.1 => /lib/x86_64-linux-gnu/libbrotlidec.so.1 (0x00007febd8607000)
        libmd.so.0 => /lib/x86_64-linux-gnu/libmd.so.0 (0x00007febd7895000)
        libsystemd.so.0 => /lib/x86_64-linux-gnu/libsystemd.so.0 (0x00007febd4331000)
        libbrotlicommon.so.1 => /lib/x86_64-linux-gnu/libbrotlicommon.so.1 (0x00007febd66dd000)
        libcap.so.2 => /lib/x86_64-linux-gnu/libcap.so.2 (0x00007febd6c17000)
        libgcrypt.so.20 => /lib/x86_64-linux-gnu/libgcrypt.so.20 (0x00007febd41ea000)
        liblzma.so.5 => /lib/x86_64-linux-gnu/liblzma.so.5 (0x00007febd66ae000)
        libzstd.so.1 => /lib/x86_64-linux-gnu/libzstd.so.1 (0x00007febd412e000)
        liblz4.so.1 => /lib/x86_64-linux-gnu/liblz4.so.1 (0x00007febd61da000)
        libgpg-error.so.0 => /lib/x86_64-linux-gnu/libgpg-error.so.0 (0x00007febd4106000)

As you can see the shared library which is not , appears like not found

    libxcb-cursor.so.0 => not found

Just thus easier to fix it , is using :

sudo apt install libxcb-cursor0

In your case could be another like: libxcb-randr0