qt.qpa.plugin: could not find the Qt platform plugin "xcb" in ""

JonB

@IknowQT said in qt.qpa.plugin: could not find the Qt platform plugin "xcb" in "":

Should the libqxcb.so file be in the path you said? As you said I don't have that file.

I believe so. Look at the other paths in the diagnostic output.

Now that I know the cause, is there a way to fix it?

Somehow by installing that file, plus any dependencies. Not my area, someone else may know. But how/what did you do to install these library files on your RPi? Did you look through some of the Google hits to see if any apply to your case?

IknowQT

@JonB

I was looking. Most recommended apt install libxcb-xinerama, but I am already up to date and the result is the same

JonB

@IknowQT
I think that is the other way round: I believe libxcb-xinerama is a library needed for the xcb library, and you have not got that far. Don't you need something like

apt install libxcb
# or
apt install libqxcb

Press the Tab key (possibly twice) at the end of these lines and the shell should show you names of whatever packages match the prefixes.

IknowQT

@JonB
It says the package you said could not be found.

JonB

@IknowQT
Are you compiling and deploying all on RPi, or are you cross-compiling for RPi from another host?
What about trying

find / -name libqxcb.so -ls 2>/dev/null

on your RPi, and also on host platform if you are cross-compiling?

What about perhaps https://forum.qt.io/topic/125582/qt-5-15-2-do-not-build-libqxcb-so-but-at-the-same-time-qt-5-14-0-successfully-build-libqxcb-so :

Seems like I fix the problem:

sudo apt-get install libxcb-util-dev

It required for build Qt 5.15.x but not required for Qt 5.14.x

?

IknowQT

@JonB

I have built a cross-compilation environment in Ubuntu and am running it by uploading it to Raspberry Pi.

find / -name libqxcb.so -ls 2>/dev/null

Here is the result I tried.

devqt@devqt-desktop:/$ find / -name libqxcb.so -ls 2>/dev/null
 29906776     12 -rwxrwxrwx   1 root     root         9680  9월 28  2020 /root/rpi-qt_32/sysroot/usr/lib/arm-linux-gnueabihf/qt5/plugins/platforms/libqxcb.so
 29127237     12 -rwxrwxrwx   1 root     root         9680  9월 28  2020 /root/rpi-qt_32/sysroot/lib/arm-linux-gnueabihf/qt5/plugins/platforms/libqxcb.so

sudo apt-get install libxcb-util-dev
It says package not found.
instead

sudo apt-get install libxcb-util0-dev
sudo apt-get install libxcb-util0

There are two packages, so I installed both, but it says that they are already installed.

JonB

@IknowQT
These look possibly like the required files. Since I know nothing about RPi or cross-compiling for it, I do not know whether these are situated on the cross-compiling machine or on the RPI target. I would guess the compiling machine, but don't know.

If they are on the compiling machine don't they need copying to the RPi?
If they are on the RPi then where are they, aren't they supposed to be in /usr/local/qt5.15/plugins/platforms or somewhere Qt plugins are sought?

I know nothing about "after depoly from qtcreator to Raspberry Pi", check whatever instructions you are using?

Earlier:

sudo apt-get install libxcb-util0-dev
sudo apt-get install libxcb-util0

and you said "It says the package you said could not be found."

If these worked did you really follow my instruction:

apt install libxcb
# or
apt install libqxcb

Press the Tab key (possibly twice) at the end of these lines and the shell should show you names of whatever packages match the prefixes

or did you just ignore what I said about the Tab key?

IknowQT

/lib/arm-linux-gnueabihf/qt5/plugins/platforms/libqxcb.so

The Raspberry Pi also has this file.
it's too hard

JonB

@IknowQT said in qt.qpa.plugin: could not find the Qt platform plugin "xcb" in "":

it's too hard

Best of luck.

SiGa

I had the same or similar issue.
libqxcb was not present in (install_dir is the path provided with -prefix during configuration)

install_dir/plugins/platforms

I had to install the recommended packages from https://doc.qt.io/qt-6/linux-requirements.html and then rebuild qt from source(configure, compile, install, copy to target).
Additionally my copy command did not copy libqxcb, so I used compressed version for copying.
In the end I was missing some libs on the target, machine. After this, it worked.
May it be helpful for some future visitor.