Maximum number of client reached

[Zbigniew Lisiecki]

H, I have a similar situation, like the one described in this thread: https://forum.qt.io/topic/127696/qt-qpa-plugin-could-not-load-the-qt-platform-plugin-xcb-in-even-though-it-was-found Yet I have QT6 from OpenSuSE 14.5 new installation, so I have no configure script and cannot follow with it. Let me give you the outputs with the kind request for help.
Zbigniew Lisiecki

---

orion:/home/zbyszek # locate libqxcb.so
/usr/lib64/qt5/plugins/platforms/libqxcb.so
/usr/lib64/qt6/plugins/platforms/libqxcb.so

libQt5Gui5 - version: 5.15.3+kde294-150400.6.3.1-x86_64
libQt6Gui6 - version: 6.2.2-150400.2.8-x86_64

orion:/home/zbyszek # export QT_DEBUG_PLUGINS=1
orion:/home/zbyszek # libreoffice
Maximum number of clients reachedMaximum number of clients reachedFailed to open display
QFactoryLoader::QFactoryLoader() checking directory path "/usr/lib64/qt5/plugins/platforms" ...
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqeglfs.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqeglfs.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"eglfs"
]
},
"archreq": 0,
"className": "QEglFSIntegrationPlugin",
"debug": false,
"version": 331520
}

Got keys from plugin meta data ("eglfs")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqlinuxfb.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqlinuxfb.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"linuxfb"
]
},
"archreq": 0,
"className": "QLinuxFbIntegrationPlugin",
"debug": false,
"version": 331520
}

Got keys from plugin meta data ("linuxfb")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqminimal.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqminimal.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"minimal"
]
},
"archreq": 0,
"className": "QMinimalIntegrationPlugin",
"debug": false,
"version": 331520
}

Got keys from plugin meta data ("minimal")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqminimalegl.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqminimalegl.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"minimalegl"
]
},
"archreq": 0,
"className": "QMinimalEglIntegrationPlugin",
"debug": false,
"version": 331520
}

Got keys from plugin meta data ("minimalegl")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqoffscreen.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqoffscreen.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"offscreen"
]
},
"archreq": 0,
"className": "QOffscreenIntegrationPlugin",
"debug": false,
"version": 331520
}

Got keys from plugin meta data ("offscreen")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqvnc.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqvnc.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"vnc"
]
},
"archreq": 0,
"className": "QVncIntegrationPlugin",
"debug": false,
"version": 331520
}

Got keys from plugin meta data ("vnc")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqwayland-egl.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqwayland-egl.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"wayland-egl"
]
},
"archreq": 0,
"className": "QWaylandEglPlatformIntegrationPlugin",
"debug": false,
"version": 331520
}

Got keys from plugin meta data ("wayland-egl")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqwayland-generic.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqwayland-generic.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"wayland"
]
},
"archreq": 0,
"className": "QWaylandIntegrationPlugin",
"debug": false,
"version": 331520
}

Got keys from plugin meta data ("wayland")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqwayland-xcomposite-egl.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqwayland-xcomposite-egl.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"wayland-xcomposite-egl"
]
},
"archreq": 0,
"className": "QWaylandXCompositeEglPlatformIntegrationPlugin",
"debug": false,
"version": 331520
}

Got keys from plugin meta data ("wayland-xcomposite-egl")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqwayland-xcomposite-glx.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqwayland-xcomposite-glx.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"wayland-xcomposite-glx"
]
},
"archreq": 0,
"className": "QWaylandXCompositeGlxPlatformIntegrationPlugin",
"debug": false,
"version": 331520
}

Got keys from plugin meta data ("wayland-xcomposite-glx")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqxcb.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqxcb.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"xcb"
]
},
"archreq": 0,
"className": "QXcbIntegrationPlugin",
"debug": false,
"version": 331520
}

Got keys from plugin meta data ("xcb")
QFactoryLoader::QFactoryLoader() checking directory path "/usr/lib64/libreoffice/program/platforms" ...
loaded library "/usr/lib64/qt5/plugins/platforms/libqxcb.so"
Maximum number of clients reachedMaximum number of clients reachedqt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" 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: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, xcb.

orion:/home/zbyszek # ldd /usr/lib64/qt6/plugins/platforms/libqxcb.so
linux-vdso.so.1 (0x00007ffc647f4000)
libQt6XcbQpa.so.6 => /usr/lib64/qt6/plugins/platforms/../../../libQt6XcbQpa.so.6 (0x00007f85cc673000)
libQt6Gui.so.6 => /usr/lib64/qt6/plugins/platforms/../../../libQt6Gui.so.6 (0x00007f85cbc64000)
libQt6Core.so.6 => /usr/lib64/qt6/plugins/platforms/../../../libQt6Core.so.6 (0x00007f85cb4e4000)
libstdc++.so.6 => /usr/lib64/qt6/plugins/platforms/../../../libstdc++.so.6 (0x00007f85cb0d1000)
libc.so.6 => /lib64/libc.so.6 (0x00007f85cacdc000)
libxcb-icccm.so.4 => /usr/lib64/qt6/plugins/platforms/../../../libxcb-icccm.so.4 (0x00007f85caad7000)
libxcb-image.so.0 => /usr/lib64/qt6/plugins/platforms/../../../libxcb-image.so.0 (0x00007f85ca8d2000)
libxcb-keysyms.so.1 => /usr/lib64/qt6/plugins/platforms/../../../libxcb-keysyms.so.1 (0x00007f85ca6cf000)
libxcb-randr.so.0 => /usr/lib64/qt6/plugins/platforms/../../../libxcb-randr.so.0 (0x00007f85ca4be000)
libxcb-render.so.0 => /usr/lib64/qt6/plugins/platforms/../../../libxcb-render.so.0 (0x00007f85ca2b0000)
libxcb-render-util.so.0 => /usr/lib64/qt6/plugins/platforms/../../../libxcb-render-util.so.0 (0x00007f85ca0ac000)
libxcb-shape.so.0 => /usr/lib64/qt6/plugins/platforms/../../../libxcb-shape.so.0 (0x00007f85c9ea8000)
libxcb-shm.so.0 => /usr/lib64/qt6/plugins/platforms/../../../libxcb-shm.so.0 (0x00007f85c9ca4000)
libxcb-sync.so.1 => /usr/lib64/qt6/plugins/platforms/../../../libxcb-sync.so.1 (0x00007f85c9a9d000)
libxcb.so.1 => /usr/lib64/qt6/plugins/platforms/../../../libxcb.so.1 (0x00007f85c9874000)
libxcb-xfixes.so.0 => /usr/lib64/qt6/plugins/platforms/../../../libxcb-xfixes.so.0 (0x00007f85c966c000)
libxcb-xkb.so.1 => /usr/lib64/qt6/plugins/platforms/../../../libxcb-xkb.so.1 (0x00007f85c944f000)
libxkbcommon.so.0 => /usr/lib64/qt6/plugins/platforms/../../../libxkbcommon.so.0 (0x00007f85c920b000)
libglib-2.0.so.0 => /usr/lib64/qt6/plugins/platforms/../../../libglib-2.0.so.0 (0x00007f85c8ed8000)
libX11-xcb.so.1 => /usr/lib64/qt6/plugins/platforms/../../../libX11-xcb.so.1 (0x00007f85c8cd6000)
libX11.so.6 => /usr/lib64/qt6/plugins/platforms/../../../libX11.so.6 (0x00007f85c8995000)
libSM.so.6 => /usr/lib64/qt6/plugins/platforms/../../../libSM.so.6 (0x00007f85c878d000)
libICE.so.6 => /usr/lib64/qt6/plugins/platforms/../../../libICE.so.6 (0x00007f85c8570000)
libxcb-xinput.so.0 => /usr/lib64/qt6/plugins/platforms/../../../libxcb-xinput.so.0 (0x00007f85c834d000)
libxkbcommon-x11.so.0 => /usr/lib64/qt6/plugins/platforms/../../../libxkbcommon-x11.so.0 (0x00007f85c8145000)
libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f85c7f22000)
libm.so.6 => /lib64/libm.so.6 (0x00007f85c7bd7000)
libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007f85c79be000)
libEGL.so.1 => /usr/lib64/qt6/plugins/platforms/../../../libEGL.so.1 (0x00007f85c77ab000)
libfontconfig.so.1 => /usr/lib64/qt6/plugins/platforms/../../../libfontconfig.so.1 (0x00007f85c7566000)
libdl.so.2 => /lib64/libdl.so.2 (0x00007f85c7362000)
libQt6DBus.so.6 => /usr/lib64/qt6/plugins/platforms/../../../libQt6DBus.so.6 (0x00007f85c70a3000)
libGLX.so.0 => /usr/lib64/qt6/plugins/platforms/../../../libGLX.so.0 (0x00007f85c6e72000)
libOpenGL.so.0 => /usr/lib64/qt6/plugins/platforms/../../../libOpenGL.so.0 (0x00007f85c6c46000)
libpng16.so.16 => /usr/lib64/qt6/plugins/platforms/../../../libpng16.so.16 (0x00007f85c6a03000)
libharfbuzz.so.0 => /usr/lib64/qt6/plugins/platforms/../../../libharfbuzz.so.0 (0x00007f85c66de000)
libfreetype.so.6 => /usr/lib64/qt6/plugins/platforms/../../../libfreetype.so.6 (0x00007f85c6420000)
libz.so.1 => /lib64/libz.so.1 (0x00007f85c6209000)
libicui18n.so.suse65.1 => /usr/lib64/qt6/plugins/platforms/../../../libicui18n.so.suse65.1 (0x00007f85c5d17000)
libicuuc.so.suse65.1 => /usr/lib64/qt6/plugins/platforms/../../../libicuuc.so.suse65.1 (0x00007f85c5938000)
libzstd.so.1 => /usr/lib64/qt6/plugins/platforms/../../../libzstd.so.1 (0x00007f85c5608000)
libsystemd.so.0 => /usr/lib64/qt6/plugins/platforms/../../../libsystemd.so.0 (0x00007f85c5326000)
libdouble-conversion.so.3 => /usr/lib64/qt6/plugins/platforms/../../../libdouble-conversion.so.3 (0x00007f85c5118000)
libb2.so.1 => /usr/lib64/qt6/plugins/platforms/../../../libb2.so.1 (0x00007f85c4f10000)
libpcre2-16.so.0 => /usr/lib64/qt6/plugins/platforms/../../../libpcre2-16.so.0 (0x00007f85c4c63000)
/lib64/ld-linux-x86-64.so.2 (0x00007f85ccb14000)
libxcb-util.so.1 => /usr/lib64/libxcb-util.so.1 (0x00007f85c4a5d000)
libXau.so.6 => /usr/lib64/libXau.so.6 (0x00007f85c4859000)
libpcre.so.1 => /usr/lib64/libpcre.so.1 (0x00007f85c45d0000)
libuuid.so.1 => /usr/lib64/libuuid.so.1 (0x00007f85c43c8000)
libGLdispatch.so.0 => /usr/lib64/libGLdispatch.so.0 (0x00007f85c4112000)
libexpat.so.1 => /usr/lib64/libexpat.so.1 (0x00007f85c3ed3000)
libdbus-1.so.3 => /usr/lib64/qt6/plugins/platforms/../../../libdbus-1.so.3 (0x00007f85c3c81000)
libgraphite2.so.3 => /usr/lib64/libgraphite2.so.3 (0x00007f85c3a5b000)
libbz2.so.1 => /usr/lib64/libbz2.so.1 (0x00007f85c383e000)
libicudata.so.suse65.1 => /usr/lib64/libicudata.so.suse65.1 (0x00007f85c363d000)
librt.so.1 => /lib64/librt.so.1 (0x00007f85c3434000)
liblzma.so.5 => /usr/lib64/liblzma.so.5 (0x00007f85c31fa000)
liblz4.so.1 => /usr/lib64/liblz4.so.1 (0x00007f85c2fd9000)
libcap.so.2 => /usr/lib64/libcap.so.2 (0x00007f85c2dcf000)
libgcrypt.so.20 => /usr/lib64/libgcrypt.so.20 (0x00007f85c2a92000)
libgomp.so.1 => /usr/lib64/libgomp.so.1 (0x00007f85c284e000)
libgpg-error.so.0 => /usr/lib64/libgpg-error.so.0 (0x00007f85c262a000)

[SGaist]

Hi and welcome to devnet,

Based on this thread I wonder whether you have too many process (or likely zombi processes) that are consuming all available connections.

[Zbigniew Lisiecki]

@SGaist Yes, I am wondering about so many opened files too. It

lsof -U  | wc
lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/1000/gvfs
      Output information may be incomplete.
lsof: WARNING: can't stat() fuse.portal file system /run/user/1000/doc
      Output information may be incomplete.
   2605   24459  247296

shows over 2600 of them. I have 10 desktops with some 50 opened firefox cards. It consumes less than 20% of processor and even less network. Most opened files are UNIX tmp sockets like the one:

X          1807       root   71u  unix 0xffff9b18af5e3b80      0t0  23972 @/tmp/.X11-unix/X0 type=STREAM

which come from the sddm desktop server

ps -alx  | grep 1807
4     0  1807  1786  20   0 554192 110344 -     Ssl+ tty7      50:41 /usr/bin/X -nolisten tcp -auth /run/sddm/{56bff3c4-6591-4e9c-9974-7bface1fa41f} -background none -noreset -displayfd 17 -seat seat0 vt7

Well, I'll try with a new Linux user and I'll show you the result. Your post shows this error might have nothing to do with QT, am I right ?

[SGaist]

Indeed, it looks highly Xorg specific. You might want to just close Firefox for a start.

[Zbigniew Lisiecki]

@SGaist Yes, I have several youtube videos, which I watch. Now I started completely new session and I have some 200 opened files without any browser beeing started. This is still a lot, but I can live with !
The above error does not appear any more.

[Zbigniew Lisiecki]

@Zbigniew-Lisiecki Yes, this was the solution. I have opened too much firefox cards and they accumulated from former sessions. Thank you SGaist. The problem can be assigned as solved.