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  4. [Solved] Qt5.2.1 Platform issue on deployment, could not find xcb plugin. Linux
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[Solved] Qt5.2.1 Platform issue on deployment, could not find xcb plugin. Linux

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  • JKSHJ Offline
    JKSHJ Offline
    JKSH
    Moderators
    wrote on last edited by
    #4

    [quote]
    @
    This application failed to start because it could not find or load the Qt platform plugin "xcb".

    Available platform plugins are: xcb.

    Reinstalling the application may fix this problem.
    @
    [/quote]I've encountered this unintuitive message before. In my case, Ubuntu found libqxcb.so but failed to load it because one of its dependencies was missing.

    Follow the quick-and-dirty method in this guide to identify the missing dependenc(ies): http://qt-project.org/wiki/Deploy_an_Application_on_Windows It's written for Windows but also works on Linux. Just replace *.dll with *.so

    Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

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    • SGaistS Offline
      SGaistS Offline
      SGaist
      Lifetime Qt Champion
      wrote on last edited by
      #5

      Hi,

      To add to JKSH, you can run ldd on your xcb plugin to see what libraries are linked and you'll also see if something is missing

      Interested in AI ? www.idiap.ch
      Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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      • A Offline
        A Offline
        Ajp1989
        wrote on last edited by
        #6

        Thanks for your responses. Think I am having some progress, or am doing it totally wrong.

        -So I orignally was using libqxcb.so from ~/Qt/5.2.1/gcc_64/plugins/platforms with no success. I thought perhaps this might be the incorrect library so I ran ldd on the source machine a picked out a version from where it was picking it's libs, /usr/lib/x86_64, this had more dependancies so I included them in the application directory.-
        -Now I get a different error-
        @
        ~Desktop/graph-deploy/./mg_linux: symbol lookup error: ~Desktop/graph-deploy/./mg_linux: undefined symbol: _ZN19QAbstractScrollArea19setSizeAdjustPolicyENS_16SizeAdjustPolicyE
        @
        -running cfilt identfies this as-
        @
        QAbstractScrollArea::setSizeAdjustPolicy(QAbstractScrollArea::SizeAdjustPolicy)
        @
        -Any ideas? Or have I gone the wrong way?-

        -Also I compiled the original on Mint 15 and am trying to get it to run on Ubuntu 12.04. Will this be an issue?-

        -I did notice that running-
        @ldd -d -r@

        -on the original libqxcb I was using returned no missing libraries but many undefined symbol references.-

        EDIT: ignore this rubbish!

        Needed to solve the symbol errors for the file libqxcb.so from /Qt/5.2.1/gcc_64/plugins/platforms

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        • A Offline
          A Offline
          Ajp1989
          wrote on last edited by
          #7

          Thanks JKSH for putting me on the way to the solution!
          [quote author="JKSH" date="1393037410"]
          Follow the quick-and-dirty method in this guide to identify the missing dependenc(ies): http://qt-project.org/wiki/Deploy_an_Application_on_Windows It's written for Windows but also works on Linux. Just replace *.dll with *.so[/quote]

          Here is a Linux version of the above for those who may have a similar problem.

          Firstly copy the required platform plugin libqxcb.so to a test directory ~/test_libs from /pathToQt/plugins/platforms in my case the pathToQt was ~/Qt/5.2.1/gcc_64/

          Then copy all of the libraries from /pathToQt/lib to ~/test_libs

          Set the LD_LIBRARY_PATH
          @
          LD_LIBRARY_PATH=~/test_libs
          export LD_LIBRARY_PATH
          @

          Then run
          @
          cd ~/test_libs
          ldd -r -d libqxcb.so
          @

          This should have no errors or undefined symbol messages.

          Then you can delete libraries from ~/test_libs whilst rerunning ldd to work out the required libs, or delete all the libraries that ldd does not list from the directory ~/test_libs.

          In my case libqxcb.so required the following libraries
          libicudata.so.51
          libicui18n.so.51
          libicuuc.so.51
          libQt5Core.so.5
          libQt5DBus.so.5
          libQt5Gui.so.5

          So I think my problem was that some incompatible libraries were found on the system so ldd didn't complain about them being missing.

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          • JKSHJ Offline
            JKSHJ Offline
            JKSH
            Moderators
            wrote on last edited by
            #8

            I'm glad that you've found a solution! Thank you for sharing your technique too.

            Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

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            • N Offline
              N Offline
              nike.niec
              wrote on last edited by
              #9

              Hi
              I am using CentOS 6.5 x86_64

              I created a GUI Application executable named "Graphitev1" using Qt5.2.1
              It is a Widget based application.

              Below are dependency for my executable:
              @
              ldd Graphitev1
              linux-vdso.so.1 => (0x00007fff2d5ff000)

                  libQt5PrintSupport.so.5 => /home/vedams/Qt5.2.1/5.2.1/gcc_64/lib/libQt5PrintSupport.so.5 (0x00007f4dc6bef000)
              
                  libQt5Widgets.so.5 => /home/vedams/Qt5.2.1/5.2.1/gcc_64/lib/libQt5Widgets.so.5 (0x00007f4dc63a8000)
              
                  libQt5Gui.so.5 => /home/vedams/Qt5.2.1/5.2.1/gcc_64/lib/libQt5Gui.so.5 (0x00007f4dc5d22000)
              
                  libQt5Core.so.5 => /home/vedams/Qt5.2.1/5.2.1/gcc_64/lib/libQt5Core.so.5 (0x00007f4dc5654000)
              
                  libGL.so.1 => /usr/lib64/libGL.so.1 (0x0000003195800000)
              
                  libpthread.so.0 => /lib64/libpthread.so.0 (0x000000318a800000)
              
                  libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x0000003196400000)
              
                  libm.so.6 => /lib64/libm.so.6 (0x000000318b400000)
              
                  libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x0000003195000000)
              
                  libc.so.6 => /lib64/libc.so.6 (0x000000318a000000)
              
                  libgobject-2.0.so.0 => /lib64/libgobject-2.0.so.0 (0x000000318c800000)
              
                  libglib-2.0.so.0 => /lib64/libglib-2.0.so.0 (0x000000318b800000)
              
                  libX11.so.6 => /usr/lib64/libX11.so.6 (0x000000318e000000)
              
                  libicui18n.so.51 => /home/vedams/Qt5.2.1/5.2.1/gcc_64/lib/libicui18n.so.51 (0x00007f4dc5226000)
              
                  libicuuc.so.51 => /home/vedams/Qt5.2.1/5.2.1/gcc_64/lib/libicuuc.so.51 (0x00007f4dc4ea0000)
              
                  libdl.so.2 => /lib64/libdl.so.2 (0x000000318a400000)
              
                  libgthread-2.0.so.0 => /lib64/libgthread-2.0.so.0 (0x000000318cc00000)
              
                  librt.so.1 => /lib64/librt.so.1 (0x000000318ac00000)
                  /lib64/ld-linux-x86-64.so.2 (0x0000003189c00000)
              
                  libglapi.so.0 => /usr/lib64/libglapi.so.0 (0x0000003197000000)
              
                  libXext.so.6 => /usr/lib64/libXext.so.6 (0x000000318e800000)
              
                  libXdamage.so.1 => /usr/lib64/libXdamage.so.1 (0x0000003191400000)
              
                  libXfixes.so.3 => /usr/lib64/libXfixes.so.3 (0x0000003192000000)
              
                  libX11-xcb.so.1 => /usr/lib64/libX11-xcb.so.1 (0x000000318f000000)
              
                  libxcb-glx.so.0 => /usr/lib64/libxcb-glx.so.0 (0x0000003196c00000)
              
                  libxcb-dri2.so.0 => /usr/lib64/libxcb-dri2.so.0 (0x0000003195c00000)
              
                  libxcb.so.1 => /usr/lib64/libxcb.so.1 (0x000000318dc00000)
              
                  libXxf86vm.so.1 => /usr/lib64/libXxf86vm.so.1 (0x0000003196000000)
              
                  libdrm.so.2 => /usr/lib64/libdrm.so.2 (0x0000003196800000)
              
                  libselinux.so.1 => /lib64/libselinux.so.1 (0x000000318bc00000)
              
                  libicudata.so.51 => /home/vedams/Qt5.2.1/5.2.1/gcc_64
              

              /lib/libicudata.so.51 (0x00007f4dc3752000)

                  libXau.so.6 => /usr/lib64/libXau.so.6 (0x000000318d800000)
              

              @

              Now i am copying this executable "Graphitev1" with dependency in another CentOS 6.5 x86_64 machine and below is contents:

              @

              ls -lh
              -rwxrwxr-x. 1 vedams vedams 4.7M May 19 18:11 Graphitev1
              lrwxrwxrwx. 1 vedams vedams 18 May 19 18:19 libicudata.so.51 -> libicudata.so.51.1
              -rwxr-xr-x. 1 vedams vedams 22M May 19 18:11 libicudata.so.51.1
              lrwxrwxrwx. 1 vedams vedams 18 May 19 18:19 libicui18n.so.51 -> libicui18n.so.51.1
              -rwxr-xr-x. 1 vedams vedams 2.6M May 19 18:11 libicui18n.so.51.1
              lrwxrwxrwx. 1 vedams vedams 16 May 19 18:18 libicuuc.so.51 -> libicuuc.so.51.1
              -rwxr-xr-x. 1 vedams vedams 1.8M May 19 18:11 libicuuc.so.51.1
              lrwxrwxrwx. 1 vedams vedams 19 May 19 18:18 libQt5Core.so.5 -> libQt5Core.so.5.2.1
              -rwxr-xr-x. 1 vedams vedams 4.8M May 19 18:11 libQt5Core.so.5.2.1
              lrwxrwxrwx. 1 vedams vedams 19 May 19 18:17 libQt5DBus.so.5 -> libQt5DBus.so.5.2.1
              -rwxr-xr-x. 1 vedams vedams 523K May 19 18:11 libQt5DBus.so.5.2.1
              lrwxrwxrwx. 1 vedams vedams 18 May 19 18:17 libQt5Gui.so.5 -> libQt5Gui.so.5.2.1
              -rwxr-xr-x. 1 vedams vedams 4.6M May 19 18:11 libQt5Gui.so.5.2.1
              lrwxrwxrwx. 1 vedams vedams 27 May 19 18:16 libQt5PrintSupport.so.5 -> libQt5PrintSupport.so.5.2.1
              -rwxr-xr-x. 1 vedams vedams 412K May 19 18:11 libQt5PrintSupport.so.5.2.1
              lrwxrwxrwx. 1 vedams vedams 22 May 19 18:12 libQt5Widgets.so.5 -> libQt5Widgets.so.5.2.1
              -rwxr-xr-x. 1 vedams vedams 6.3M May 19 18:11 libQt5Widgets.so.5.2.1
              -rwxr-xr-x. 1 vedams vedams 1.4M May 19 18:11 libqxcb.so
              @

              now i exported the LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$PWD

              now when i ran the application, i got the error

              @

              This application failed to start because it could not find or load the Qt platform plugin "xcb".

              Reinstalling the application may fix this problem.
              Aborted (core dumped)
              @

              Please tell me in simple manner , how to resolve this error
              I m getting lost in above thread and following other links

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              • A Offline
                A Offline
                Ajp1989
                wrote on last edited by
                #10

                libqxcb.so needs to reside in a folder called platforms within the application source.

                I found it very annoying when I had this error meassge to solve.

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                • N Offline
                  N Offline
                  nike.niec
                  wrote on last edited by
                  #11

                  Thanks a lot Ajp1989.Its working
                  But can yu please explain the reason behind this

                  And can yu give the standard procedure to pack applcation to deliver it to client.Currently for testing purpose i hardcoded lot of things.
                  By Target Machine and development machines are CentOS-6.5 x86_64
                  And i am developing a Desktop Widget based Application

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                  0
                  • hskoglundH Offline
                    hskoglundH Offline
                    hskoglund
                    wrote on last edited by
                    #12

                    Hi, I also had problems before when deploying to Ubuntu machines. I wrote about it in 2 blog posts: "how to deploy":http://www.tripleboot.org/?p=138 (scroll down to Linux GCC...) and "why you need":http://www.tripleboot.org/?p=536 that platforms directory.

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                    • N Offline
                      N Offline
                      nike.niec
                      wrote on last edited by
                      #13

                      Thanks,surely i will look into your blog

                      1 Reply Last reply
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