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qt.qpa.plugin: could not find the Qt platform plugin "xcb" in ""

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  • J JonB
    10 Jun 2022, 07:48

    @IknowQT
    There are many possibilities if you Google for e.g.
    qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in ""

    So far as I can see you do not have any xcb plugin library installed at all. You should have a file /usr/local/qt5.15/plugins/platforms/libqxcb.so, but I do not think you even have that? In which case, how did you install what? I am not an expert, but if it is supposed to come from your XCB Xlib ............................. yes line I don't think it has been installed on your RPi?

    I Offline
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    IknowQT
    wrote on 10 Jun 2022, 07:58 last edited by
    #4

    @JonB

    Should the libqxcb.so file be in the path you said? As you said I don't have that file.

    Now that I know the cause, is there a way to fix it?

    J 1 Reply Last reply 10 Jun 2022, 08:05
    0
    • I IknowQT
      10 Jun 2022, 07:58

      @JonB

      Should the libqxcb.so file be in the path you said? As you said I don't have that file.

      Now that I know the cause, is there a way to fix it?

      J Offline
      J Offline
      JonB
      wrote on 10 Jun 2022, 08:05 last edited by
      #5

      @IknowQT said in qt.qpa.plugin: could not find the Qt platform plugin "xcb" in "":

      Should the libqxcb.so file be in the path you said? As you said I don't have that file.

      I believe so. Look at the other paths in the diagnostic output.

      Now that I know the cause, is there a way to fix it?

      Somehow by installing that file, plus any dependencies. Not my area, someone else may know. But how/what did you do to install these library files on your RPi? Did you look through some of the Google hits to see if any apply to your case?

      I 1 Reply Last reply 10 Jun 2022, 08:12
      0
      • J JonB
        10 Jun 2022, 08:05

        @IknowQT said in qt.qpa.plugin: could not find the Qt platform plugin "xcb" in "":

        Should the libqxcb.so file be in the path you said? As you said I don't have that file.

        I believe so. Look at the other paths in the diagnostic output.

        Now that I know the cause, is there a way to fix it?

        Somehow by installing that file, plus any dependencies. Not my area, someone else may know. But how/what did you do to install these library files on your RPi? Did you look through some of the Google hits to see if any apply to your case?

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        IknowQT
        wrote on 10 Jun 2022, 08:12 last edited by
        #6

        @JonB

        I was looking. Most recommended apt install libxcb-xinerama, but I am already up to date and the result is the same

        J 1 Reply Last reply 10 Jun 2022, 08:18
        0
        • I IknowQT
          10 Jun 2022, 08:12

          @JonB

          I was looking. Most recommended apt install libxcb-xinerama, but I am already up to date and the result is the same

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          J Offline
          JonB
          wrote on 10 Jun 2022, 08:18 last edited by JonB 6 Oct 2022, 08:19
          #7

          @IknowQT
          I think that is the other way round: I believe libxcb-xinerama is a library needed for the xcb library, and you have not got that far. Don't you need something like

          apt install libxcb
          # or
          apt install libqxcb
          

          Press the Tab key (possibly twice) at the end of these lines and the shell should show you names of whatever packages match the prefixes.

          I 1 Reply Last reply 10 Jun 2022, 08:20
          0
          • J JonB
            10 Jun 2022, 08:18

            @IknowQT
            I think that is the other way round: I believe libxcb-xinerama is a library needed for the xcb library, and you have not got that far. Don't you need something like

            apt install libxcb
            # or
            apt install libqxcb
            

            Press the Tab key (possibly twice) at the end of these lines and the shell should show you names of whatever packages match the prefixes.

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            I Offline
            IknowQT
            wrote on 10 Jun 2022, 08:20 last edited by
            #8

            @JonB
            It says the package you said could not be found.

            J 1 Reply Last reply 10 Jun 2022, 08:27
            0
            • I IknowQT
              10 Jun 2022, 08:20

              @JonB
              It says the package you said could not be found.

              J Offline
              J Offline
              JonB
              wrote on 10 Jun 2022, 08:27 last edited by JonB 6 Oct 2022, 08:32
              #9

              @IknowQT
              Are you compiling and deploying all on RPi, or are you cross-compiling for RPi from another host?
              What about trying

              find / -name libqxcb.so -ls 2>/dev/null
              

              on your RPi, and also on host platform if you are cross-compiling?

              What about perhaps https://forum.qt.io/topic/125582/qt-5-15-2-do-not-build-libqxcb-so-but-at-the-same-time-qt-5-14-0-successfully-build-libqxcb-so :

              Seems like I fix the problem:

              sudo apt-get install libxcb-util-dev

              It required for build Qt 5.15.x but not required for Qt 5.14.x

              ?

              I 1 Reply Last reply 10 Jun 2022, 08:41
              0
              • J JonB
                10 Jun 2022, 08:27

                @IknowQT
                Are you compiling and deploying all on RPi, or are you cross-compiling for RPi from another host?
                What about trying

                find / -name libqxcb.so -ls 2>/dev/null
                

                on your RPi, and also on host platform if you are cross-compiling?

                What about perhaps https://forum.qt.io/topic/125582/qt-5-15-2-do-not-build-libqxcb-so-but-at-the-same-time-qt-5-14-0-successfully-build-libqxcb-so :

                Seems like I fix the problem:

                sudo apt-get install libxcb-util-dev

                It required for build Qt 5.15.x but not required for Qt 5.14.x

                ?

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                IknowQT
                wrote on 10 Jun 2022, 08:41 last edited by
                #10

                @JonB

                I have built a cross-compilation environment in Ubuntu and am running it by uploading it to Raspberry Pi.

                find / -name libqxcb.so -ls 2>/dev/null

                Here is the result I tried.

                devqt@devqt-desktop:/$ find / -name libqxcb.so -ls 2>/dev/null
                 29906776     12 -rwxrwxrwx   1 root     root         9680  9월 28  2020 /root/rpi-qt_32/sysroot/usr/lib/arm-linux-gnueabihf/qt5/plugins/platforms/libqxcb.so
                 29127237     12 -rwxrwxrwx   1 root     root         9680  9월 28  2020 /root/rpi-qt_32/sysroot/lib/arm-linux-gnueabihf/qt5/plugins/platforms/libqxcb.so
                

                sudo apt-get install libxcb-util-dev
                It says package not found.
                instead

                sudo apt-get install libxcb-util0-dev
                sudo apt-get install libxcb-util0

                There are two packages, so I installed both, but it says that they are already installed.

                J 1 Reply Last reply 10 Jun 2022, 08:51
                0
                • I IknowQT
                  10 Jun 2022, 08:41

                  @JonB

                  I have built a cross-compilation environment in Ubuntu and am running it by uploading it to Raspberry Pi.

                  find / -name libqxcb.so -ls 2>/dev/null

                  Here is the result I tried.

                  devqt@devqt-desktop:/$ find / -name libqxcb.so -ls 2>/dev/null
                   29906776     12 -rwxrwxrwx   1 root     root         9680  9월 28  2020 /root/rpi-qt_32/sysroot/usr/lib/arm-linux-gnueabihf/qt5/plugins/platforms/libqxcb.so
                   29127237     12 -rwxrwxrwx   1 root     root         9680  9월 28  2020 /root/rpi-qt_32/sysroot/lib/arm-linux-gnueabihf/qt5/plugins/platforms/libqxcb.so
                  

                  sudo apt-get install libxcb-util-dev
                  It says package not found.
                  instead

                  sudo apt-get install libxcb-util0-dev
                  sudo apt-get install libxcb-util0

                  There are two packages, so I installed both, but it says that they are already installed.

                  J Offline
                  J Offline
                  JonB
                  wrote on 10 Jun 2022, 08:51 last edited by JonB 6 Oct 2022, 08:55
                  #11

                  @IknowQT
                  These look possibly like the required files. Since I know nothing about RPi or cross-compiling for it, I do not know whether these are situated on the cross-compiling machine or on the RPI target. I would guess the compiling machine, but don't know.

                  • If they are on the compiling machine don't they need copying to the RPi?
                  • If they are on the RPi then where are they, aren't they supposed to be in /usr/local/qt5.15/plugins/platforms or somewhere Qt plugins are sought?

                  I know nothing about "after depoly from qtcreator to Raspberry Pi", check whatever instructions you are using?

                  Earlier:

                  sudo apt-get install libxcb-util0-dev
                  sudo apt-get install libxcb-util0

                  and you said "It says the package you said could not be found."

                  If these worked did you really follow my instruction:

                  apt install libxcb
                  # or
                  apt install libqxcb
                  

                  Press the Tab key (possibly twice) at the end of these lines and the shell should show you names of whatever packages match the prefixes

                  or did you just ignore what I said about the Tab key?

                  1 Reply Last reply
                  0
                  • I Offline
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                    IknowQT
                    wrote on 10 Jun 2022, 08:56 last edited by
                    #12
                    /lib/arm-linux-gnueabihf/qt5/plugins/platforms/libqxcb.so
                    

                    The Raspberry Pi also has this file.
                    it's too hard

                    J 1 Reply Last reply 10 Jun 2022, 08:56
                    0
                    • I IknowQT
                      10 Jun 2022, 08:56
                      /lib/arm-linux-gnueabihf/qt5/plugins/platforms/libqxcb.so
                      

                      The Raspberry Pi also has this file.
                      it's too hard

                      J Offline
                      J Offline
                      JonB
                      wrote on 10 Jun 2022, 08:56 last edited by
                      #13

                      @IknowQT said in qt.qpa.plugin: could not find the Qt platform plugin "xcb" in "":

                      it's too hard

                      Best of luck.

                      S 1 Reply Last reply 1 Mar 2024, 15:54
                      0
                      • J JonB
                        10 Jun 2022, 08:56

                        @IknowQT said in qt.qpa.plugin: could not find the Qt platform plugin "xcb" in "":

                        it's too hard

                        Best of luck.

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                        S Offline
                        SiGa
                        wrote on 1 Mar 2024, 15:54 last edited by
                        #14

                        I had the same or similar issue.
                        libqxcb was not present in (install_dir is the path provided with -prefix during configuration)

                        install_dir/plugins/platforms
                        

                        I had to install the recommended packages from https://doc.qt.io/qt-6/linux-requirements.html and then rebuild qt from source(configure, compile, install, copy to target).
                        Additionally my copy command did not copy libqxcb, so I used compressed version for copying.
                        In the end I was missing some libs on the target, machine. After this, it worked.
                        May it be helpful for some future visitor.

                        1 Reply Last reply
                        0
                        • SGaistS SGaist has marked this topic as solved on 1 Mar 2024, 19:20

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