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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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  • A Offline
    A Offline
    Ajp1989
    wrote on last edited by
    #3

    Yes, I did follow the Qt 5 documentation, I just linked the wrong one here.

    I have copied the script and renamed it. I know LD_LIBRARY_PATH is set correctly as program doesn't complain about missing libraries when run from script (gives xcb error). Running direclty gives an error about a missing lib.

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    0
    • 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

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