I wrote application for linux which uses Qt5.
But when I am trying to launch it on the linux without Qt SDK installed, the output in console is:
Failed to load platform plugin "xcb". Available platforms are:
How can I fix this? May be I need to copy some plugin file?
When I use ubuntu with Qt5 installed, but I rename Qt directory, the same problem occurs. So, it uses some file from Qt directory...
UPDATE:
when I create in the app dir "platforms" folder with the file libqxcb.so, the app still doesnot start, but the error message changes:
Failed to load platform plugin "xcb". Available platforms are:
xcb
How can this happen? How can platform plugin be available but can't be loaded?
Use ldd (man ldd) to show shared library dependencies. Running this on libqxcb.so
.../platforms$ ldd libqxcb.so
shows that xcb depends on libQt5DBus.so.5 in addition to libQt5Core.so.5 and libQt5Gui.so.5 (and many other system libs). Add libQt5DBus.so.5 to your collection of shared libs and you should be ready to move on.
As was posted earlier, you need to make sure you install the platform plugins when you deploy your application. Depending on how you want to deploy things, there are two methods to tell your application where the platform plugins (e.g. platforms/plugins/libqxcb.so) are at runtime which may work for you.
The first is to export the path to the directory through the QT_QPA_PLATFORM_PLUGIN_PATH variable.
QT_QPA_PLATFORM_PLUGIN_PATH=path/to/plugins ./my_qt_app
or
export QT_QPA_PLATFORM_PLUGIN_PATH=path/to/plugins
./my_qt_app
The other option, which I prefer is to create a qt.conf file in the same directory as your executable. The contents of which would be:
[Paths]
Plugins=/path/to/plugins
More information regarding this can be found here and at using qt.conf
I tried to start my binary, compiled with Qt 5.7, on Ubuntu 16.04 LTS where Qt 5.5 is preinstalled. It didn't work.
At first, I inspected the binary itself with ldd as was suggested here, and satisfied all "not found" dependencies. Then this notorious This application failed to start because it could not find or load the Qt platform plugin "xcb" error was thrown.
How to resolve this in Linux
Firstly you should create platforms directory where your binary is, because it is the place where Qt looks for XCB library. Copy libqxcb.so there. I wonder why authors of other answers didn't mention this.
Then you may want to run your binary with QT_DEBUG_PLUGINS=1 environment variable set to check which dependencies of libqxcb.so are not satisfied. (You may also use ldd for this as suggested in the accepted answer).
The command output may look like this:
me#xerus:/media/sf_Qt/Package$ LD_LIBRARY_PATH=. QT_DEBUG_PLUGINS=1 ./Binary
QFactoryLoader::QFactoryLoader() checking directory path "/media/sf_Qt/Package/platforms" ...
QFactoryLoader::QFactoryLoader() looking at "/media/sf_Qt/Package/platforms/libqxcb.so"
Found metadata in lib /media/sf_Qt/Package/platforms/libqxcb.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"xcb"
]
},
"className": "QXcbIntegrationPlugin",
"debug": false,
"version": 329472
}
Got keys from plugin meta data ("xcb")
loaded library "/media/sf_Qt/Package/platforms/libqxcb.so"
QLibraryPrivate::loadPlugin failed on "/media/sf_Qt/Package/platforms/libqxcb.so" : "Cannot load library /media/sf_Qt/Package/platforms/libqxcb.so: (/usr/lib/x86_64-linux-gnu/libQt5DBus.so.5: version `Qt_5' not found (required by ./libQt5XcbQpa.so.5))"
This application failed to start because it could not find or load the Qt platform plugin "xcb"
in "".
Available platform plugins are: xcb.
Reinstalling the application may fix this problem.
Aborted (core dumped)
Note the failing libQt5DBus.so.5 library. Copy it to your libraries path, in my case it was the same directory where my binary is (hence LD_LIBRARY_PATH=.). Repeat this process until all dependencies are satisfied.
P.S. thanks to the author of this answer for QT_DEBUG_PLUGINS=1.
I tried the main parts of each answer, to no avail. What finally fixed it for me was to export the following environment variables:
LD_LIBRARY_PATH=/usr/local/lib:~/Qt/5.9.1/gcc_64/lib
QT_QPA_PLATFORM_PLUGIN_PATH=~/Qt/5.9.1/gcc_64/plugins/
Ubuntu 16.04 64bit.
I got the problem for apparently no reasons. The night before I watched a movie on my VideoLan instance, that night I would like to watch another one with VideoLan. VLC just didn't want to run because of the error into the question.
I google a bit and I found the solution it solved my problem: from now on, VLC is runnable just like before. The solution is this comand:
sudo ln -sf /usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/ /usr/bin/
I am not able to explain what are its consequencies, but I know it creates some missing symbolic link.
Since version 5, Qt uses a platform abstraction system (QPA) to abstract from the underlying platform.
The implementation for each platform is provided by plugins. For X11 it is the XCB plugin. See Qt for X11 requirements for more information about the dependencies.
There might be many causes to this problem. The key is to use
export QT_DEBUG_PLUGINS=1
before you run your Qt application. Then, inspect the output, which will point you to the direction of the error. In my case it was:
Cannot load library /opt/nao/plugins/platforms/libqxcb.so: (/opt/nao/bin/../lib/libz.so.1: version `ZLIB_1.2.9' not found (required by /usr/lib/x86_64-linux-gnu/libpng16.so.16))
But that is solved in different threads. See for instance https://stackoverflow.com/a/50097275/2408964.
Probably this information will help. I was on Ubuntu 18.04 and when I tried to install Krita, using the ppa method, I got this error:
This application failed to start because it could not find or load the Qt platform plugin "xcb" in "".
Available platform plugins are: linuxfb, minimal, minimalegl, offscreen, wayland-egl, wayland, xcb.
Reinstalling the application may fix this problem.
Aborted
I tried all the solutions that I found in this thread and other webs without any success.
Finally, I found a post where the author mention that is possible to activate the debugging tool of qt5 using this simple command:
export QT_DEBUG_PLUGINS=1
After adding this command I run again krita I got the same error, however this time I knew the cause of that error.
libxcb-xinerama.so.0: cannot open shared object file: No such file or directory.
This error prevents to the "xcb" to load properly. So, the solution will be install the `libxcb-xinerama.so.0" right? However, when I run the command:
sudo apt install libxcb-xinerama
The lib was already installed. Now what Teo? Well, then I used an old trick :) Yeah, that one --reinstall
sudo apt install --reinstall libxcb-xinerama
TLDR: This last command solved my problem.
I ran into a very similar problem with the same error message. First, debug some by turning on the Qt Debug printer with the command line command:
export QT_DEBUG_PLUGINS=1
and rerun the application. For me this revealed the following:
"Cannot load library /home/.../miniconda3/lib/python3.7/site-packages/PyQt5/Qt/plugins/platforms/libqxcb.so: (libxkbcommon-x11.so.0: cannot open shared object file: No such file or directory)"
"Cannot load library /home/.../miniconda3/lib/python3.7/site-packages/PyQt5/Qt/plugins/platforms/libqxcb.so: (libxkbcommon-x11.so.0: cannot open shared object file: No such file or directory)"
Indeed, I was missing libxkbcommon-x11.so.0 and libxkbcommon-x11.so.0. Next, check your architecture using dpkg from the linux command line. (For me, the command "arch" gave a different and unhelpful result)
dpkg --print-architecture #result for me: amd64
I then googled "libxkbcommon-x11.so.0 ubuntu 18.04 amd64", and likewise for libxkbcommon-x11.so.0, which yields those packages on packages.ubuntu.com. That told me, in retrospect unsurprisingly, I'm missing packages called libxkbcommon-x11-0 and libxkbcommon0, and that installing those packages will include the needed files, but the dev versions will not. Then the solution:
sudo apt-get update
sudo apt-get install libxkbcommon0
sudo apt-get install libxkbcommon-x11-0
So, I spent about a day trying to figure out what was the issue; tried all the proposed solutions, but none of that worked like installing xcb libs or exporting Qt plugins folder. The solution that suggested to use QT_DEBUG_PLUGINS=1 to debug the issue didn't provide me a direct insight like in the answer - instead I was getting something about unresolved symbols within Qt5Core.
That gave me a hint, though: what if it's trying to use different files from different Qt installations? On my machine I had standard version installed in /home/username/Qt/ and some local builds within my project that I compiled by myself (I have other custom built kits as well in other locations). Whenever I tried to use any of the kits (installed by Qt maintenance tool or built by myself), I would get an "xcb error".
The solution was simple: provide the Qt path through CMAKE_PREFIX_PATH and not though Qt5_DIR as I did, and it solved the problem. Example:
cmake .. -DCMAKE_PREFIX_PATH=/home/username/Qt/5.11.1/gcc_64
I faced the same problem when after installing Viber. It had all required qt libraries in /opt/viber/plugins/.
I checked dependencies of /opt/viber/plugins/platforms/libqxcb.so and found missing dependencies. They were libxcb-render.so.0, libxcb-image.so.0, libxcb-icccm.so.4, libxcb-xkb.so.1
So I resolved my issue by installing missing packages with this libraries:
apt-get install libxcb-xkb1 libxcb-icccm4 libxcb-image0 libxcb-render-util0
I like the solution with qt.conf.
Put qt.conf near to the executable with next lines:
[Paths]
Prefix = /path/to/qtbase
And it works like a charm :^)
For a working example:
[Paths]
Prefix = /home/user/SDKS/Qt/5.6.2/5.6/gcc_64/
The documentation on this is here: https://doc.qt.io/qt-5/qt-conf.html
All you need to do is
pip uninstall PyQt5
and
conda install pyqt
Most of the problem of pyqt can be fixed by this simplest solution.
In my case, I needed to deploy two Qt apps on an Ubuntu virtualbox guest. One was command-line ("app"), the other GUI_based ("app_GUI").
I used "ldd app" to find out what the required libs are, and copied them
to the Ubuntu guest.
While the command-line executable "app" worked ok, the GUI-based executable crashed, giving
the "Failed to load platform plugin "xcb" error. I checked ldd for libxcb.so, but this too had no missing dependencies.
The problem seemed to be that while I did copy all the right libraries I accidentally had copied also libraries that were already present at the guest system.. meaning that (a) they were unnecessary to copy them in the first place and (b) worse, copying them produced incompatibilities between the install libraries.
Worse still, they were undetectable by ldd like I said..
The solution? Make sure that you copy libraries shown as missing by ldd and absolutely no extra libraries.
In my case missing header files were the reason libxcb was not built by Qt. Installing them according to https://wiki.qt.io/Building_Qt_5_from_Git#Linux.2FX11 resolved the issue:
yum install libxcb libxcb-devel xcb-util xcb-util-devel mesa-libGL-devel libxkbcommon-devel
Folks trying to get this started on Ubuntu 20.04 please try to run this and see if this solves the problem. This worked for me
sudo apt-get update -y
sudo apt-get install -y libxcb-xinerama0
I link all Qt stuff statically to the generic Linux builds of my open source projects. It makes life a bit easier. You just need to build static versions of Qt libraries first. Of course this cannot be applied to closed source software due to licensing issues. The deployment of Qt5 apps on Linux is currently a bit problematic, because Ubuntu 12.04, for example, doesn't have Qt5 libraries in the package repositories.
I had this problem, and on a hunch I removed the Qt Configs from my environment. I.e.,
rm -rf ~/.config/Qt*
Then I started qtcreator and it reconfigured itself with the existing state of the machine. It no longer remembered where my projects were, but that just meant I had to browse to them "for the first time" again.
But more importantly it built itself a coherent set of library paths, so I could rebuild and run my project executables again without the xcb or qxcb libraries going missing.
I faced the same situation, but on a Ubuntu 20.04 VM.
TL;DR: Check file permissions.
What I did:
I copied the Qt libs required to /usr/local/lib/x86_64-linux-gnu/ and added it to LD_LIBRARY_PATH
I copied the platforms folder from Qt to my application directory and added it to QT_PLUGIN_PATH
I ran ldd on the executable and in the offending libqxcb.so (ldd libqxcb.so), and it complains about some dependencies although ldconfig listed them as found.
linux-vdso.so.1 (0x00007ffee19af000)
libQt5XcbQpa.so.5 => not found
libfontconfig.so.1 => /lib/x86_64-linux-gnu/libfontconfig.so.1 (0x00007f7cb18fb000)
libfreetype.so.6 => /lib/x86_64-linux-gnu/libfreetype.so.6 (0x00007f7cb183c000)
libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f7cb1820000)
libQt5Gui.so.5 => /usr/local/lib/x86_64-linux-gnu/libQt5Gui.so.5 (0x00007f7cb0fd4000)
libQt5DBus.so.5 => not found
I used export QT_DEBUG_PLUGINS=1 for further info. It complains about missing files, although they are there.
What I found:
For some reason, when copying to the VM through the shared folder the files permissions were not the correct ones.
Thus, I ran: sudo chmod 775 * on the libs and voilà.
I solved the issue through this https://github.com/NVlabs/instant-ngp/discussions/300
pip uninstall opencv-python
pip install opencv-python-headless
This seems to have been a problem with the cv2 Python package and how it loops in Qt
sudo ln -sf /usr/lib/...."adapt-it"..../qt5/plugins/platforms/ /usr/bin/
It creates the symbolic link it's missed. Good for QT ! Good for VLC !!
I was building the openresty Nginx on machine A and want to use it on machine B. Is it necessary to install all the rpm/dependencies on machine B?
The building process on machine A is like:
yum install multiple-devel commands
git clone multiple repositories
wget openresty.tar.gz
untar openresty, cd openresty and ./configure --...
gmake
gmake install
When I tried to understand the relationships between configure, make and make install, I found https://stackoverflow.com/a/54628708/11887927 but still not quite get it.
If it's still required to install all the rpm&dependencies, what's the benefit of building on my own or I'm totally wrong about the make process?
Maybe I didn't make myself clear enough. Thanks for anyone stopping by.
Machine B doesn't require rpm/dependencies but needs libraries built on machine A
Here is how it works:
copy Nginx binary/configurations to B
copy libraries(including folders, openresty in my case) to B
echo libraries to /etc/ld.so.conf.d, /etc/ld.so.conf.d/luajit.conf in my case
I appreciate that this is borderline off-topic, but it does "directly involve programming or programming tools" so I figure it's just about OK...
I've just installed a newly downloaded version of Git for Windows, and noticed that in the Options dialog, the title bar says "mintty 2.8.5 is available". According to the About dialog, I currently have version 2.8.4.
I assume it's telling me that there's a new version because I am able to upgrade it myself, but I can't find any information about how to do so. I've downloaded the zip file from mintty.github.io, but don't really want to have to build it manually if I can avoid it.
Is there some way to do this, or is the easiest option just to wait for an updated build of Git For Windows that includes the new version of MinTTY?
mintty is a terminal emulator program available for Cygwin and msys2 environment. In both environment, mintty can be compiled as 32bit and 64bit. Hence it will be easy to deploy if users/package maintainer compile themselves with their own toolchain. Here are the two mainstream toolchain associated with mintty.
Cygwin: You can search the full package namecygwin package search. Cygwin maintains multiple mirror URLs to download a package. Here is one of the mirror:
32bit: https://mirrors.kernel.org/sourceware/cygwin/x86/release/mintty/
64bit: https://mirrors.kernel.org/sourceware/cygwin/x86_64/release/mintty/
msys2: msys2 also maintains mirror URLs to download. You can browse whole packages list in http://repo.msys2.org/. Open that URL in a browser. As mintty need msys2 dynamic library, it can be found in msys2 directory. Search mintty in these webpages:
32bit: http://repo.msys2.org/msys/i686/
64bit: http://repo.msys2.org/msys/x86_64/
To use it in Git-For-Windows, download the mintty tarball file from msys2 links according to your installed one 32bit or 64bit. You can find mintty.exe in that .tar.xz file's usr/bin folder. Extract and place that executable in Git-For-Windows installation folder e.g. C:\Program Files\Git\usr\bin.
Note: Mintty need a dynamic library (e.g. cygwin1.dll or msys-2.0.dll) and a shell (e.g. bash.exe, dash.exe etc.) or a command line program to run. And it should be placed in /usr/bin or /bin folder as per your specific environment. For Cygwin specifically, you also need cygwin-console-helper.exe to hide the console window (conhost.exe process). In msys2 environment, mintty version may be lower than the Cygwin one.
I was having a similar issue with Git Bash saying "mintty 3.5.2 available". I simply used the following command in Git Bash.
git update-git-for-windows
It re-ran the installer and updated both my Git for Windows and mintty versions to the latest ones. The command is only valid from Git for Windows v2.16.1(2) though.
Very nooby question, but I'm trying to install Atom text editor on Raspbian Stretch. Is it possible? I've heard because it runs on Electron, it's quite slow for Raspbian. I keep getting an error saying:
E: Unable to locate package atom
I'm following the official instructions for Debian. How can I fix this?
As of today you can't install the official package provided for Debian for its mismatching the hardware platform. Provided binary is for running on x86 hardware, but RPi doesn't come with an Intel/AMD processor, but ARM. So, you most probably need to build it from source yourself.
Primer
So, if you really want to build this from source, you should be aware of the waste of disk space caused by the IMHO poorly implemented build tool which is downloading tons of deps and copying and transpiling code around so you'll end up with 2GB+ of files with 80% accounting to dependencies, only. Since my RPi works with 8GB smartcard, only, I couldn't ever meet the need for disk space even though I was bleeding out Linux by manually removing docs, manpages, locales, ton's of outdated and mostly unused apps etc. The build also requires a whole build tooling chain, tons of dev packages for libraries, so there is a limit to milk the system ... 8GB disk drive simply isn't enough for this.
Eventually I tried moving all the files to a USB pen drive. But that drive must be formatted using a filesystem capable of symlinking. So you can't use vfat or FAT32. I didn't succeed to get a 16GB stick formatted with either version of extfs. The mkfs always ended up in a deadlock on trying to write its superblocks. Astonishingly, I couldn't even kill the mkfs with -KILL, but unplugging the drive did help in that case.
So, as a conclusion: here is a short list of steps I passed in expectation to get this working, but in the end I didn't finish due to the memory issues above. And frankly, I stopped caring ... I'd rather work with nano/vi in a terminal than using this ridiculous lego-like built software. I guess, atom is today's version of emacs with regards to the latter's acronym. Maybe you succeed with this, but I won't ...
Build from Source
Inspired by https://discuss.atom.io/t/atom-on-the-raspberry-pi/33332
Install toolchain for building native stuff
sudo apt-get install build-essential git libgnome-keyring-dev fakeroot gconf2 gconf-service libgtk2.0-0 libudev1 libgcrypt20 python rpm libsecret-1-dev xorg-dev
This set of tools was sufficient to build core files without error. Since I didn't start with a fresh installation of Raspbian there might have been some tool I have been using before, so maybe in your case there are more tools to be installed here. Look out for error messages in early stage of building and try to see if some library or header file isn't found. This mostly indicates lack of some package with name ending in -dev to be installed, too. Start by searching for the package using apt search <name-of-mentioned-library> and look for a package combining the missing library's name with suffix -dev. Then install it the usual way by invoking sudo apt-get install <package-name>.
Install up-to-date nodejs
Raspbian Stretch comes with support for NodeJS 8.11 which is basically okay. Install it and its package manager npm using this command:
sudo apt-get install node-js npm
Check installed versions with
node -v
npm -v
This should display 8.x.x on behalf of NodeJs. Use n afterwards if you want to step up:
sudo npm i -g n
sudo n lts
This will switch NodeJS to latest LTS release, which is 10.x as of now. Upgrading NodeJS is optional, but feel advised to always use latest version of npm:
sudo npm i -g npm
Check if upgrades succeeded:
node -v
npm -v
Adjust configuration of npm and install some essential dep:
sudo npm config set -g python /usr/bin/python2
sudo npm i -g node-gyp
Build Atom
Get the source. One option is to pull latest code from its repository:
git clone https://github.com/atom/atom.git
This is creating subfolder atom containing all source files. You might want to download sources of a recent release instead. But this tutorial was made with the sources fetched from Github. So make sure there is subfolder called atom containing sources similar to the ones fetched above.
It's time to start the beast:
cd atom
./script/build
This process will take a while. And it is the culprit that never finished on success in my case due to eating up all disk space over and over again.
Whenever the script fails on error, try to analyze the error, find the cause, fix it, then start the script by repeating the last command above again. If you don't remove any file in subfolder atom in between, the build script keeps passing steps of building atom it has passed successfully before.
Install atom
According to the original tutorial linked before the script should finish on success eventually. Then it's time to install with:
./script/grunt install
I guess this is causing atom to be available as a command from CLI. So, try it out. If everything looks fine you are finally ready to remove the waste of files in subfolder atom.
Feel free to report if this was working in your case.
From what I recall Atom runs 64-bit architecture; need the latest raspberry Pi.
run the following
wget https://atom.io/download/deb && dpkg -i deb
Coming from Ubuntu I bought a new iMac and tried to setup my Qt development. Everything else is already up and running. Xcode command line tools are also installed.
Because it surprised me how good brewand brew caskworked I wanted to install Qt5with them. On the one side it is very fast and I do not have to got to any homepage in order to download it. On the other side I do not have to care about the installation directory. Having multiple version installed should also be a lot simpler though.
I used the following commands:
brew install qt5
brew cask install qt-creator
Qt5 is now installed under /usr/local/Cellar/qt5/5.4.1. I also added the bin folder to my path (done in .bash_profile). QtCreator, Linguist and all the other applications are shown in my launchpad. But unfortunately, it is still not done.
QtCreator says that no version of Qt is known. I tried to add qmake but I was not able to navigate to the folder mentioned above.
Could anybody give me a hint on how to fix this issue? Installing qt via installer should be the last option.
I had similar issue with Qt Creator, now on Mac GUI applications do not have access to environmental variables (in previous versions it was different).
You need to setup path to qmake in Qt Creator manually using Command-Shift-G in Finder to navigate to Folder you need.
Another option is to use brew link qt5 --force, which will symlink the various Qt5 binaries and libraries into your /usr/local/bin and /usr/local/lib directories. This will give you qmake at the command line, without requiring you to add anything special to your path in .bash_profile. The main reason this isn't done by default is that Qt4 is also somewhat popular.
It could get a little messy, but if you need to install Qt4 as well, you can unlink Qt5 at any time, by doing brew unlink qt5, and it will keep the installation intact. Then do brew install qt to get Qt4, which unlike the brew installation for Qt5 will indeed create the links directly into /usr/local without you having to manually do brew link qt. You can unlink Qt4 and relink Qt5 (or vice-versa) whenever you need to switch.
In my cases I needed to set it in Preferences => QT Versions => Add. Environment variables also did not help. Small popup when starting app also did not work.
I use command like this:
brew install qt#5
and. success install qt5 by brew.