I followed this guide and installed emscripten using emsdk and activated it.Then I configured my $PATH as instructed by the emsdk itself and also sourced emsdk-master/emsdk_env.sh.Now I can access both emcc and em++ in the terminal.The file ~/.emscripten is also present(this is the file that QtCreator will fetch to find the path of compilers for WASM).
The WebAssembly kit for Qt also has been installed by the Qt Maintenance Tool.
Now in the Kit configuration in the QtCreator I get this(QtCreator is opened via terminal after sourcing emsdk_env.sh):
It cannot determine the path of compilers by itself.
In the Compilers tab I manually added a compiler as follows:
But I get this error in the Kits tab after that:
What does that mean? What did I skip? Does anybody ever have the experience of doing this?
Also changing the compiler from em++ to wasm-32-wasi-clang++ or clang++ doesn't change anything.
By the way if I use that kit I get:
Error while parsing file whatever.pro. Giving up.
Project ERROR: Cannot run target compiler 'em++'. Output:
===================
===================
Maybe you forgot to setup the environment?
And please don't tell me that this question is the duplicate of this because it isn't(mine has more details) and there's no useful answer for that after 9 months at this time.
Any help is much appreciated.
Make sure you run:
emsdk install
and
emsdk activate
within emsdk folder, not from a relative path.
You have to setup the emsdk inside QtCreator => Preferences => Devices => WebAssembly. Afterwards the compiler should be auto-detected by Qt Creator.
I had the same problem and the solution was, that python was not correctly recognized.
In my case the symbolic link /usr/bin/python was not set
ln -sf /usr/bin/python3 /usr/bin/python
Afterwards the emsripten Toolchain is recognized automatically in QtCreator.
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'm trying to compile geany-plugins-1.28. The debugger plugin (the only one I need) gives the error:
debug.c:53:21: fatal error: vte/vte.h: No such file or directory
#include <vte/vte.h>
Clearly it needs to know where this file is located to compile. I found the vte.h file in the src directory of the main program geany-1.28. When running
sudo ./configure cflags=-I/home/pi/Desktop/geany-1.28/src
I get the same error about the missing header later trying to compile the debugger plugin.
I ran
./configure --help
to get all the flag options. The output is here
How do I get this to configure correctly so that it compiles. I need to compile the debugger version 1.28 myself because apt only installs 1.24 which I think has a bug because it crashes when I run my code with the error:
close failed in file object destructor:
sys.execpthook is missing
lost sys.stderr
CFLAGS is case-sensitive environment variable, so you should set it before running configure, not try to pass it as a command line argument. This variant:
$ export CFLAGS=-I/home/pi/Desktop/geany-1.28/src
$ ./configure
leaves CFLAGS set for current shell until you leave it. While this:
$ CFLAGS=-I/home/pi/Desktop/geany-1.28/src ./configure
sets variable only for current command, i.e. configure.
Some other issues:
You do not need sudo to configure and make. It is also unnecessary for make install if you set PREFIX to a path you have privileges to write to.
Does plugin's build system also builds all it's dependencies? If not, you may face linker errors a bit later.
Update:
I have tried to build debugger plugin and got rid of your error. It seems that vte.h coming with Geany is it's intrinsic, while the plugin requires full-featured file from the library. So I just installed vte and vte-devel from repos. Nevertheless, I got some other unrelated errors coming from Glib. I will not continue my attempts to build all this right now. Hope my effort will be helpful at least a little.
As in this answer stated, vte.h is not the file you are looking for. Install libvte(-dev) package on your system and rerun configure.
Just for the record: vte.h on Geany is a dummy to allow Geany to kind of dynamical enable vte or disable it depending on vte is installed on the system or not.
I am trying to build NetCDF4 from source on MacOSX. When I run ./configure I get the error:
checking for library containing H5Fflush... no
configure: error: Can't find or link to the hdf5 library. Use --disable-netcdf-4, or see config.log for errors.
I installed hdf5 before, and set the environment variables as:
LDFLAGS=-L/opt/local/lib
CPPFLAGS=-I/opt/local/include
In /opt/local/lib I have these files:
libhdf5.8.dylib
libhdf5.a
libhdf5.dylib
libhdf5.settings
libhdf5_cpp.8.dylib
libhdf5_cpp.a
libhdf5_cpp.dylib
libhdf5_hl.8.dylib
libhdf5_hl.a
libhdf5_hl.dylib
libhdf5_hl_cpp.8.dylib
libhdf5_hl_cpp.a
libhdf5_hl_cpp.dylib
And in /opt/local/include I have:
hdf5.h hdf5_hl.h
Why doesn't the configure script find the hdf5 library? I am happy to provide more information if needed!
EDIT:
My ultimate goal is to install netcdf4 for use as a Fortran module. I have tried installing everything through MacPorts, and it seemed to work, but when I tried to use it, the compiler told me that there was no netcdf.mod file, and sure enough there wasn't one to be found anywhere.
It turns out that just typing:
sudo port install netcdf-fortran
only installs the library files, but doesn't create a .mod file, which I guess is needed. So I found out that other people had the same problem, and the advice given was to install it with gcc44, which did create a .mod file, but then my compiler told me that the .mod file was built with a different version of gfortran and it couldn't be used, so that's why I am trying to build it from scratch, but if someone has a faster option, I would be more than happy to try it!
Ok, I finally figured it out.
I reinstalled netcdf-fortran with macports, then the .mod file suddenly appeared, I then had the problem, however, that when running gfortran, it would tell me that netcdf.mod was compiled with a different version of fortran than the one I am using. (Macports uses 4.8), so got gcc48 from macports and am using gfortran-mp-4.8 to compile now and it works.
Still don't know how to build all these things from scratch, but it works now at least!!!
Typically, I see this when there is a downstream dependency that cannot be fulfilled. The test program created by configure is finding libhdf5, but compilation is still failing because it cannot find something like libz or libszip, depending on how your libhdf5 was compiled.
If you check your config.log file and look for the error, it will probably tell you something along the lines of 'unresolved symbol'. This will give a clue as to which library is missing. If it is linking against the statically-built libhdf5, you may need to add the appropriate library usingLDFLAGS.
If you post the relevant portion of your config.log file, we may be able to help sort out what exactly is going wrong.
Sometimes it doesn't work in the configure parameters like
./configure --enable-shared --enable-fortran --enable-netcdf-4
CPPFLAGS=-I$home/apps2/include LDFALGS=-L$home/apps2/lib --prefix=$home/apps2
or doesn't work when export CPPFLAGS=-I$home/apps2/include in the open SHELL.
Maybe you can set the env vars CPPFLAGS and LDFLAGS in the .bashrc file (prior to the first two ways).