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

[SGaist]

Hi

@actionmystique why are you trying to run a GUI application as root ?

How did you become root in the first place ?

[actionmystique]

@SGaist

why are you trying to run a GUI application as root ?

root is required to run /usr/bin/env which is used in the script. I do no see any reason why being root may be the root ;-) cause for this issue.

How did you become root in the first place ?

Does it really matter?

[JonB]

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

root is required to run /usr/bin/env

I do not know what platform/variant of Linux you are on, but since when has running /usr/bin/env ever required root permission/user to run??

I do no see any reason why being root may be the root ;-) cause for this issue.

Xorg does not like a root user to run UI applications if you are logged into it as a non-root user. (I don't know whether xhost +... would permit this.) I imagine that is why @SGaist is asking.

[actionmystique]

@JonB

I do not know what platform/variant of Linux you are on, but since when has running /usr/bin/env ever required root permission/user to run??

I did not phrase it correctly; pkexec needs root to run env ; the script contains:

pkexec env DISPLAY="$DISPLAY" XAUTHORITY="$XAUTHORITY" "$seadoctorDir"/exec-seatools-in-dir

[JonB]

@actionmystique
If you are running as root but not logged on as root I still wonder if that is the issue.

Xorg

By default, and for security reasons, root will be unable to connect to a non-root user's X server. There are multiple ways of allowing root to do so however, if necessary.

https://wiki.archlinux.org/title/Running_GUI_applications_as_root

Maybe this is an issue, maybe it is not.

[actionmystique]

@JonB
I tried:

1. login as root: same result
2. add one policy kit file for env and for SeaTools: same result
   org.freedesktop.policykit.pkexec.policy

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE policyconfig PUBLIC
 "-//freedesktop//DTD PolicyKit Policy Configuration 1.0//EN"
 "http://www.freedesktop.org/standards/PolicyKit/1/policyconfig.dtd">
<policyconfig>
  <action id="org.freedesktop.policykit.pkexec.run-env">
    <description>Run env</description>
    <message>Authentication is required to run env</message>
    <defaults>
      <allow_any>no</allow_any>
      <allow_inactive>no</allow_inactive>
      <allow_active>auth_admin_keep</allow_active>
    </defaults>
    <annotate key="org.freedesktop.policykit.exec.path">/usr/bin/env</annotate>
    <annotate key="org.freedesktop.policykit.exec.allow_gui">TRUE</annotate>
  </action>
  <action id="org.freedesktop.policykit.pkexec.run-SeaTools">
    <description>Run SeaTools</description>
    <message>Authentication is required to run SeaTools</message>
    <defaults>
      <allow_any>no</allow_any>
      <allow_inactive>no</allow_inactive>
      <allow_active>auth_admin_keep</allow_active>
    </defaults>
    <annotate key="org.freedesktop.policykit.exec.path">/opt/SeaTools5/SeaTools</annotate>
    <annotate key="org.freedesktop.policykit.exec.allow_gui">TRUE</annotate>
  </action>
</policyconfig>

However, I did notice one file which may or may not be adequate: qt.conf

# Generated by linuxdeployqt
# https://github.com/probonopd/linuxdeployqt/
[Paths]
Prefix = ./
Plugins = plugins
Imports = qml
Qml2Imports = qml

[actionmystique]

Has anyone tried to run SeaTools from seagate on Ubuntu?

[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.