Error running statically-linked application... Could not find the Qt platform plugin "xcb"

Daniel Williams

I've read a bunch of posts on this subject, but I'm not sure, yet, what the solution is.

I have a subdirs project name, InPlantScanner, that I created with a standard install of Qt on Ubuntu 16.04 lts. It runs fine when I run it from Qt creator and the command line. Now I need to get it ready for deployment to the destination computer. I don't want to install Qt on the computer (though I could) to keep the maintenance more simple. When I update the application, it updates everything needed.

So, I'm following the instructions at: https://doc.qt.io/qt-5/linux-deployment.html for x11 deployment. I had some challenges and received help in the forums getting the statically-linked Qt setup (https://forum.qt.io/topic/104112/clarification-of-path-to-qt-in-qt-documentation/2)

Now, I have built my application with the 5.12.4, statically-linked Qt. When I run my application (./IPSgui), I get some errors:

QFactoryLoader::QFactoryLoader() ignoring "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3" since plugins are disabled in static builds

qt.qpa.plugin, Could not find the Qt platform plugin "xcb" in ""

From some of the posts I read, I thought I should re-compile the Qt-5124 with the -qt-xcb option, but that didn't work.

$ ../Qt/5.12.4/Src/configure -static -prefix ~/qt-5124 -qt-xcb

ERROR: Feature 'xcb' was enabled, but the pre-condition 'features.thread && features.xkbcommon && libs.xcb' failed.

I could keep adding dependencies to the compilation, but I'm not sure what to specify to include features.thread and features.xkbcommon.

I have 2 questions:

Will continuting to add the dependencies like I started with -qt-xcb work eventually?
Is there a better path?

Pablo J. Rogina

@Daniel-Williams do you have X11 development libraries and headers installed in the machine where you try to build static Qt?

Daniel Williams

@Pablo-J-Rogina I had run the apt-get install previously to make sure they were installed:

 sudo apt-get install libx11-dev
Reading package lists... Done
Building dependency tree       
Reading state information... Done
libx11-dev is already the newest version (2:1.6.3-1ubuntu2.1).

They were installed previously. The part of you reply "where you try to build static Qt" is not familiar to me. Do I need to copy them from the base install location somewhere?

SGaist

Hi,

@Daniel-Williams said in Error running statically-linked application... Could not find the Qt platform plugin "xcb":

features.xkbcommon

Do you have the xkbcommon development package installed ?

Daniel Williams

@SGaist How do I tell if I have xkbcommon installed? I tried sudo apt-get install xkbcommon and received an error "unable to locate packate xkbcommon."

Daniel Williams

@SGaist I was able to run sudo apt-get install libxkbcommon-dev and it installed the package.

SGaist

Good, did that solve your build problem ?

Daniel Williams

@SGaist Unfortunately not. I also expanded that with:

sudo apt install '^libxcb.*-dev' libx11-xcb-dev libglu1-mesa-dev libxrender-dev libxi-dev

In the ~/qt-5124-build/config.log file, I see some errors, but I'm not sure how to resolve the errors. I tried to attach the file, but I don't have privileges for that.

Sample error messages:


executing config test c++1z
+ cd /home/inplant/qt-5124-build/config.tests/c++1z && /home/inplant/qt-5124-build/qtbase/bin/qmake "CONFIG -= qt debug_and_release app_bundle lib_bundle" "CONFIG += static use_gold_linker warn_off console single_arch" /home/inplant/qt-5124-build/config.tests/c++1z
+ cd /home/inplant/qt-5124-build/config.tests/c++1z && MAKEFLAGS= /usr/bin/make
> g++ -c -pipe -O2 -std=gnu++1z -w -fPIC  -I. -I/home/inplant/Qt/5.12.4/Src/qtbase/mkspecs/linux-g++ -o main.o main.cpp
> main.cpp:8:19: fatal error: variant: No such file or directory
> compilation terminated.
> Makefile:167: recipe for target 'main.o' failed
> make: *** [main.o] Error 1

Trying source 2 (type inline) of library dbus ...
None of [libdbus-1.so libdbus-1.a] found in [] and global paths.
  => source produced no result.
test config.qtbase.libraries.dbus FAILED

Trying source 1 (type inline) of library libudev ...
None of [libudev.so libudev.a] found in [] and global paths.
  => source produced no result.
test config.qtbase.libraries.libudev FAILED

Daniel Williams

I thought I'd give some more detail of what I'm doing in case I'm missing a step:

Linux ubuntu 4.15.0-52-generic #56~16.04.1-Ubuntu SMP Thu Jun 6 12:03:31 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux running in a VMWare virtual machine on a windows 10 computer.

I originally installed Qt open source. It installed a kit (5.12.1 and I later upgraded to 5.12.4).
The kit I have is located at ~/Qt/5.12.4.

That was all I had while I was developing the subdirs project (InPlantScanner). When I build using that kit, it builds
to ~/scannerRD/builds/release/InPlantScanner. Using this application I can run the program just fine. All of
the necessary libraries are on the system and the application works great.

Now, I'm ready to deploy the appliation to a physical server running the same version of linux. For simplicity,
I decided to deploy it as a statically-linked application. I want to be able to take the build directory,
copy it to the destination server and have it run.

I followed these directions:
https://doc.qt.io/qt-5/linux-deployment.html

cd ~
mkdir qt-5124
mkdir qt-5124-build
cd ~/qt-5124-build
../Qt/5.12.4/Src/configure -static -prefix ~/qt-5124

make -j 4 #make the build
make install #install to ~/qt-5124

#After several hours, the install was complete.
#I opened the subdirs project, InPlantScanner, in Qt creator. I added a new kit with the statically-linked
#version of Qt. I set the project to build to ~/scannerRD/builds/staticallylinked/release/InPlantScanner

#I re-built the application in Qt creator and it built successfully.

cd ~/scannerRD/builds/staticallylinked/release/InPlantScanner/IPSguid
./IPSgui

#I then look in the logs and see the error I listed at the beginning of this post.

#There are some errors in the config.log file. But, I have no idea how to fix them.
#I'm attaching the latest config.log file.

#For Example, I see this error on line 175:
175 > g++ -c -pipe -O2 -std=gnu++1z -w -fPIC -I. -I/home/inplant/Qt/5.12.4/Src/qtbase/mkspecs/linux-g++ -o main.o main.cpp
176 > main.cpp:8:19: fatal error: variant: No such file or directory
177 > compilation terminated.
178 > Makefile:167: recipe for target 'main.o' failed
179 > make: *** [main.o] Error 1
180 test config.qtbase.tests.c++1z FAILED

#I don't know what main is in relation to the Qt source code. How do I fix that.

Daniel Williams

This is what I ultimately had to do to resolve the issue:

sudo apt install libxkbcommon-dev
sudo apt install '^libxcb.*-dev' libx11-xcb-dev libglu1-mesa-dev libxrender-dev libxi-dev

../Qt/5.12.4/Src/configure -static -prefix ~/qt-5124 -system-xcb -recheck-all

Note:
I had a build directory that I used for an interim build location: ~/qt-5124-build. In that directory, there were two very useful file:
config.log
config.summary