qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in ""
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Installation and Deployment
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Hello everyone!
I'm new in using Qt tools.
I want to build from source Qt 5.12.12, on CentOS Linux release 7.7.1908 (Core).
I'm working on an HPC cluster so I don't have root. I installed all libraries and tools in a personal directory.
I successfully installed Qt, but while I want to launch Cube, I have an error message (already used QT_DEBUG_PLUGINS=1):Got keys from plugin meta data ("webgl") QFactoryLoader::QFactoryLoader() checking directory path "[MY_CUBEGUI_INSTALL_PATH]/cubegui-4.8/bin/platforms" ... qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in "" This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem. Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, webgl.It seems there is not libqxcb.so library in my plugins directory, here is the result of ls:
libqeglfs.so libqlinuxfb.so libqminimalegl.so libqminimal.so libqoffscreen.so libqvnc.so libqwebgl.soI found similar errors in the page, but their message is:
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.which is not exactly the same as what I have.
Could anyone help me to find the problem? Thank you!
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@gaoyiqin95 said in qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in "":
I successfully installed Qt
You mean you built it from source?
In that case check config.log file in the build folder, it should tell you why xcb plug-in build was disabled (probably some library is missing). -
@gaoyiqin95
in my platforms dir of Qt-5.15.5, these libs are installed.
libqeglfs.so
libqminimalegl.so
libqoffscreen.so
libqwayland-egl.so
libqwayland-xcomposite-egl.so
libqxcb.so
libqlinuxfb.so
libqminimal.so
libqvnc.so
libqwayland-generic.so
libqwayland-xcomposite-glx.soYou may not have libqxcb.so. Check your installation flags out and make sure this one is installed.
An easy way to do this might be:
install CentOS Linux release 7.7 in a virtual machine and use online installer to install Qt under /opt/Qt(default location).
Then you can copy the whole installed Qt dir to your HPC machine. -
@jsulm
Thank you for response. But there are so much information in config.log that I can't identify what is useful for solving my problem. In contrast, here is what I have in config.summary:Build type: linux-g++ (x86_64, CPU features: mmx sse sse2) Compiler: gcc 9.3.0 Configuration: use_gold_linker sse2 aesni sse3 ssse3 sse4_1 sse4_2 avx avx2 avx512f avx512bw avx512cd avx512dq avx512er avx512ifma avx512pf avx512vbmi avx512vl compile_examples enable_new_dtags f16c largefile precompile_header rdrnd shani x86SimdAlways shared rpath release c++11 c++14 c++1z concurrent dbus reduce_exports reduce_relocations stl Build options: Mode ................................... release Optimize release build for size ........ no Building shared libraries .............. yes Using C standard ....................... C11 Using C++ standard ..................... C++1z Using ccache ........................... no Using gold linker ...................... yes Using new DTAGS ........................ yes Using precompiled headers .............. yes Using LTCG ............................. no Target compiler supports: SSE .................................. SSE2 SSE3 SSSE3 SSE4.1 SSE4.2 AVX .................................. AVX AVX2 AVX512 ............................... F ER CD PF DQ BW VL IFMA VBMI Other x86 ............................ AES F16C RDRAND SHA Intrinsics without -mXXX option ...... yes Build parts ............................ libs tools Qt modules and options: Qt Concurrent .......................... yes Qt D-Bus ............................... yes Qt D-Bus directly linked to libdbus .... no Qt Gui ................................. yes Qt Network ............................. yes Qt Sql ................................. yes Qt Testlib ............................. yes Qt Widgets ............................. yes Qt Xml ................................. yes Support enabled for: Using pkg-config ....................... yes udev ................................... no Using system zlib ...................... yes Qt Core: DoubleConversion ....................... yes Using system DoubleConversion ........ no GLib ................................... yes iconv .................................. yes ICU .................................... no Tracing backend ........................ <none> Logging backends: journald ............................. no syslog ............................... no slog2 ................................ no Using system PCRE2 ..................... no Qt Network: getifaddrs() ........................... yes IPv6 ifname ............................ yes libproxy ............................... no Linux AF_NETLINK ....................... yes OpenSSL ................................ yes Qt directly linked to OpenSSL ........ no OpenSSL 1.1 ............................ no DTLS ................................... yes SCTP ................................... no Use system proxies ..................... yes Qt Gui: Accessibility .......................... yes FreeType ............................... yes Using system FreeType ................ yes HarfBuzz ............................... yes Using system HarfBuzz ................ no Fontconfig ............................. yes Image formats: GIF .................................. yes ICO .................................. yes JPEG ................................. yes Using system libjpeg ............... yes PNG .................................. yes Using system libpng ................ yes EGL .................................... yes OpenVG ................................. no OpenGL: Desktop OpenGL ....................... yes OpenGL ES 2.0 ........................ no OpenGL ES 3.0 ........................ no OpenGL ES 3.1 ........................ no OpenGL ES 3.2 ........................ no Vulkan ................................. no Session Management ..................... yes Features used by QPA backends: evdev .................................. yes libinput ............................... no INTEGRITY HID .......................... no mtdev .................................. no tslib .................................. no xkbcommon .............................. no X11 specific: XLib ................................. yes XCB Xlib ............................. yes EGL on X11 ........................... yes QPA backends: DirectFB ............................... no EGLFS .................................. yes EGLFS details: EGLFS OpenWFD ........................ no EGLFS i.Mx6 .......................... no EGLFS i.Mx6 Wayland .................. no EGLFS RCAR ........................... no EGLFS EGLDevice ...................... yes EGLFS GBM ............................ no EGLFS VSP2 ........................... no EGLFS Mali ........................... no EGLFS Raspberry Pi ................... no EGLFS X11 ............................ yes LinuxFB ................................ yes VNC .................................... yes Mir client ............................. no Qt Sql: SQL item models ........................ yes Qt Widgets: GTK+ ................................... no Styles ................................. Fusion Windows Qt PrintSupport: CUPS ................................... no Qt Sql Drivers: DB2 (IBM) .............................. no InterBase .............................. no MySql .................................. no OCI (Oracle) ........................... no ODBC ................................... no PostgreSQL ............................. no SQLite2 ................................ no SQLite ................................. yes Using system provided SQLite ......... no TDS (Sybase) ........................... no Qt Testlib: Tester for item models ................. yes Qt SerialBus: Socket CAN ............................. yes Socket CAN FD .......................... yes Further Image Formats: JasPer ................................. no MNG .................................... no TIFF ................................... yes Using system libtiff ................. no WEBP ................................... yes Using system libwebp ................. no Qt QML: QML network support .................... yes QML debugging and profiling support .... yes QML sequence object .................... yes QML list model ......................... yes QML XML http request ................... yes QML Locale ............................. yes QML delegate model ..................... yes Qt Quick: Direct3D 12 ............................ no AnimatedImage item ..................... yes Canvas item ............................ yes Support for Qt Quick Designer .......... yes Flipable item .......................... yes GridView item .......................... yes ListView item .......................... yes TableView item ......................... yes Path support ........................... yes PathView item .......................... yes Positioner items ....................... yes Repeater item .......................... yes ShaderEffect item ...................... yes Sprite item ............................ yes Qt Scxml: ECMAScript data model for QtScxml ...... yes Qt Gamepad: SDL2 ................................... no Qt 3D: Assimp ................................. yes System Assimp .......................... no Output Qt3D Job traces ................. no Output Qt3D GL traces .................. no Use SSE2 instructions .................. yes Use AVX2 instructions .................. no Aspects: Render aspect ........................ yes Input aspect ......................... yes Logic aspect ......................... yes Animation aspect ..................... yes Extras aspect ........................ yes Qt 3D Renderers: OpenGL Renderer ........................ yes Qt 3D GeometryLoaders: Autodesk FBX ........................... no Qt Wayland Client ........................ no Qt Wayland Compositor .................... no Qt Bluetooth: BlueZ .................................. no BlueZ Low Energy ....................... no Linux Crypto API ....................... no WinRT Bluetooth API (desktop & UWP) .... no Qt Sensors: sensorfw ............................... no Qt Quick Controls 2: Styles ................................. Default Fusion Imagine Material Universal Qt Quick Templates 2: Hover support .......................... yes Multi-touch support .................... yes Qt Positioning: Gypsy GPS Daemon ....................... no WinRT Geolocation API .................. no Qt Location: Qt.labs.location experimental QML plugin . yes Geoservice plugins: OpenStreetMap ........................ yes HERE ................................. yes Esri ................................. yes Mapbox ............................... yes MapboxGL ............................. yes Itemsoverlay ......................... yes QtXmlPatterns: XML schema support ..................... yes Qt Multimedia: ALSA ................................... no GStreamer 1.0 .......................... no GStreamer 0.10 ......................... no Video for Linux ........................ yes OpenAL ................................. no PulseAudio ............................. no Resource Policy (libresourceqt5) ....... no Windows Audio Services ................. no DirectShow ............................. no Windows Media Foundation ............... no Qt Tools: QDoc ................................... no Qt WebEngine: Embedded build ......................... no Full debug information ................. no Pepper Plugins ......................... yes Printing and PDF ....................... yes Proprietary Codecs ..................... no Spellchecker ........................... yes Native Spellchecker .................... no WebRTC ................................. yes Use System Ninja ....................... no Geolocation ............................ yes WebChannel support ..................... yes Use v8 snapshot ........................ yes Kerberos Authentication ................ no Support qpa-xcb ........................ no Use ALSA ............................... no Use PulseAudio ......................... no Optional system libraries used: re2 .................................. no icu .................................. no libwebp, libwebpmux and libwebpdemux . no opus ................................. no ffmpeg ............................... no libvpx ............................... no snappy ............................... no glib ................................. yes zlib ................................. yes minizip .............................. no libevent ............................. no jsoncpp .............................. no protobuf ............................. no libxml2 and libxslt .................. no lcms2 ................................ no png .................................. no JPEG ................................. no harfbuzz ............................. no freetype ............................. yes Required system libraries: fontconfig ........................... yes dbus ................................. no nss .................................. no khr .................................. yes glibc ................................ yes Required system libraries for qpa-xcb: x11 .................................. yes libdrm ............................... yes xcomposite ........................... no xcursor .............................. no xi ................................... no xtst ................................. no Note: Also available for Linux: linux-clang linux-icc Note: No wayland-egl support detected. Cross-toolkit compatibility disabled. WARNING: QDoc will not be compiled, probably because libclang could not be located. This means that you cannot build the Qt documentation. Either ensure that llvm-config is in your PATH environment variable, or set LLVM_INSTALL_DIR to the location of your llvm installation. On Linux systems, you may be able to install libclang by installing the libclang-dev or libclang-devel package, depending on your distribution. On macOS, you can use Homebrew's llvm package. On Windows, you must set LLVM_INSTALL_DIR to the installation path. -
@gaoyiqin95 said in qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in "":
config.log that I can't identify what is useful for solving my problem
You can simply use the search function in your text editor to search for xcb
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@jsulm OK thanks. Here is information related to xcb I found in the log file:
looking for library xcb Trying source 0 (type pkgConfig) of library xcb ... + /usr/bin/pkg-config --exists --silence-errors xcb '>=' 1.9 + /usr/bin/pkg-config --modversion xcb '>=' 1.9 > 1.13 + /usr/bin/pkg-config --libs-only-L xcb '>=' 1.9 > + /usr/bin/pkg-config --libs-only-l xcb '>=' 1.9 > -lxcb + /usr/bin/pkg-config --cflags xcb '>=' 1.9 > + cd /lustre/home/acct-hpc/hpcgyq/install/qt5/x86_build/config.tests/xcb && /lustre/home/acct-hpc/hpcgyq/install/qt5/x86_build/qtbase/bin/qmake "CONFIG -= qt debug_and_release app_bundle lib_bundle" "CONFIG += shared use_gold_linker warn_off console single_arch" 'QMAKE_USE += xcb' 'QMAKE_LIBS_XCB = /lib64/libxcb.so' /lustre/home/acct-hpc/hpcgyq/install/qt5/x86_build/config.tests/xcb + cd /lustre/home/acct-hpc/hpcgyq/install/qt5/x86_build/config.tests/xcb && MAKEFLAGS= /usr/bin/gmake > g++ -c -pipe -O2 -w -fPIC -I. -I/lustre/home/acct-hpc/hpcgyq/install/qt5/qtbase/mkspecs/linux-g++ -o main.o main.cpp > g++ -Wl,-O1 -fuse-ld=gold -o xcb main.o /lib64/libxcb.so => source accepted. test config.qtbase_gui.libraries.xcb succeeded looking for library xcb_xlib Trying source 0 (type pkgConfig) of library xcb_xlib ... + /usr/bin/pkg-config --exists --silence-errors x11-xcb + /usr/bin/pkg-config --modversion x11-xcb > 1.6.7 + /usr/bin/pkg-config --libs-only-L x11-xcb > + /usr/bin/pkg-config --libs-only-l x11-xcb > -lX11-xcb -lX11 -lxcb + /usr/bin/pkg-config --cflags x11-xcb > + cd /lustre/home/acct-hpc/hpcgyq/install/qt5/x86_build/config.tests/xcb_xlib && /lustre/home/acct-hpc/hpcgyq/install/qt5/x86_build/qtbase/bin/qmake "CONFIG -= qt debug_and_release app_bundle lib_bundle" "CONFIG += shared use_gold_linker warn_off console single_arch" 'QMAKE_USE += xcb_xlib' 'QMAKE_LIBS_XCB_XLIB = /lib64/libX11-xcb.so' 'QMAKE_DEPENDS_XCB_XLIB_CC = XCB XLIB' 'QMAKE_DEPENDS_XCB_XLIB_LD = XCB XLIB' 'QMAKE_LIBS_XLIB = /lib64/libXext.so /lib64/libX11.so /lib64/libm.so' 'QMAKE_LIBS_XCB = /lib64/libxcb.so' /lustre/home/acct-hpc/hpcgyq/install/qt5/x86_build/config.tests/xcb_xlib + cd /lustre/home/acct-hpc/hpcgyq/install/qt5/x86_build/config.tests/xcb_xlib && MAKEFLAGS= /usr/bin/gmake > g++ -c -pipe -O2 -w -fPIC -I. -I/lustre/home/acct-hpc/hpcgyq/install/qt5/qtbase/mkspecs/linux-g++ -o main.o main.cpp > g++ -Wl,-O1 -fuse-ld=gold -o xcb_xlib main.o /lib64/libX11-xcb.so /lib64/libxcb.so /lib64/libXext.so /lib64/libX11.so /lib64/libm.so => source accepted. test config.qtbase_gui.libraries.xcb_xlib succeededtest config.qtbase_gui.tests.qpa_default_platform gave result xcb looking for library harfbuzz Trying source 0 (type inline) of library harfbuzz ... None of [libharfbuzz.so libharfbuzz.a] found in [] and global paths. => source produced no result.It seems that I miss library harfbuzz?
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@gaoyiqin95 said in qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in "":
test config.qtbase_gui.tests.qpa_default_platform gave result xcb
It looks like xcb check is fine.
Also from what you posted before:X11 specific: XLib ................................. yes XCB Xlib ............................. yes EGL on X11 ........................... yesSo, the plug-in should be built.
You will need to check the build log to see what happens during the build.
Check the build log (make) and also install step (make install).
