This application failed to start because no Qt platform plugin could be initialized

[PaulZ]

Re: problem with qt.qpa.plugin: running on a docker in Kubuntu

Hi. Im trying to run wbots inside the docker container with x11 but getting an error

docker-compose up webots_simulation                                                         ✔  10980  12:25:26
[+] Running 1/1
 ✔ Container shatun-webots_simulation-1  Recreated                                                                                                           0.5s
Attaching to webots_simulation-1
webots_simulation-1  | Debug: checking directory path "/usr/local/webots/lib/webots/qt/plugins/platforms" ...
webots_simulation-1  | Debug: looking at "/usr/local/webots/lib/webots/qt/plugins/platforms/libqxcb.so"
webots_simulation-1  | Debug: Found metadata in lib /usr/local/webots/lib/webots/qt/plugins/platforms/libqxcb.so, metadata=
webots_simulation-1  | {
webots_simulation-1  |     "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
webots_simulation-1  |     "MetaData": {
webots_simulation-1  |         "Keys": [
webots_simulation-1  |             "xcb"
webots_simulation-1  |         ]
webots_simulation-1  |     },
webots_simulation-1  |     "archlevel": 1,
webots_simulation-1  |     "className": "QXcbIntegrationPlugin",
webots_simulation-1  |     "debug": false,
webots_simulation-1  |     "version": 394240
webots_simulation-1  | }
webots_simulation-1  |
webots_simulation-1  |
webots_simulation-1  | Debug: Got keys from plugin meta data QList("xcb")
webots_simulation-1  | Debug: checking directory path "/usr/local/webots/bin/platforms" ...
webots_simulation-1  | Debug: "/usr/local/webots/lib/webots/qt/plugins/platforms/libqxcb.so" loaded library
webots_simulation-1  | Warning: could not connect to display host.docker.internal:0
webots_simulation-1  | Info: Could not load the Qt platform plugin "xcb" in "" even though it was found.
webots_simulation-1  | Fatal: This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
webots_simulation-1  |
webots_simulation-1  | Available platform plugins are: xcb.
webots_simulation-1  |
webots_simulation-1  | /usr/local/webots/webots: line 105:     9 Aborted                 "$webots_home/bin/webots-bin" "$@"
webots_simulation-1 exited with code 134

The Dockerfile im using is

ARG BASE_IMAGE=nvidia/cuda:11.8.0-base-ubuntu22.04
FROM ${BASE_IMAGE} AS downloader

# Determine Webots version to be used and set default argument
ARG WEBOTS_VERSION=R2023b
ARG WEBOTS_PACKAGE_PREFIX=

# Disable dpkg/gdebi interactive dialogs
ENV DEBIAN_FRONTEND=noninteractive

RUN apt-get update && apt-get install --yes wget bzip2 && rm -rf /var/lib/apt/lists/ && \
 wget https://github.com/cyberbotics/webots/releases/download/$WEBOTS_VERSION/webots-$WEBOTS_VERSION-x86-64$WEBOTS_PACKAGE_PREFIX.tar.bz2 && \
 tar xjf webots-*.tar.bz2 && rm webots-*.tar.bz2

FROM ${BASE_IMAGE}

# Disable dpkg/gdebi interactive dialogs
ENV DEBIAN_FRONTEND=noninteractive

# Install Webots runtime dependencies
RUN apt-get update && apt-get install --yes wget xvfb locales && rm -rf /var/lib/apt/lists/ && \
  wget https://raw.githubusercontent.com/cyberbotics/webots/master/scripts/install/linux_runtime_dependencies.sh && \
  chmod +x linux_runtime_dependencies.sh && ./linux_runtime_dependencies.sh && rm ./linux_runtime_dependencies.sh && rm -rf /var/lib/apt/lists/

# Install Webots
WORKDIR /usr/local
COPY --from=downloader /webots /usr/local/webots/
ENV QTWEBENGINE_DISABLE_SANDBOX=1
ENV WEBOTS_HOME /usr/local/webots
ENV PATH /usr/local/webots:${PATH}

# Set a user name to fix a warning
ENV USER root

# Set the locales
RUN locale-gen en_US.UTF-8
ENV LANG='en_US.UTF-8' LANGUAGE='en_US:en' LC_ALL='en_US.UTF-8'

RUN apt-get update && apt-get install -y '^libxcb.*-dev' libx11-xcb-dev libglu1-mesa-dev libxrender-dev libxi-dev libxkbcommon-dev libxkbcommon-x11-dev 

and docker-compose

  webots_simulation:
    build:
      context: .
      dockerfile: Dockerfile_webots_simulation
    volumes:
      - /tmp/.X11-unix:/tmp/.X11-unix
    environment:
      - DISPLAY=host.docker.internal:0
      - QT_DEBUG_PLUGINS=1
      - QT_X11_NO_MITSHM=1
    command: webots

Does anyone can help to understand what is a problem? Running on Mac OS

[jsulm]

@PaulZ said in This application failed to start because no Qt platform plugin could be initialized:

Warning: could not connect to display host.docker.internal:0

This is the problem.
Is X11 running when you start the app?

[PaulZ]

@jsulm yes

xhost + 127.0.0.1

works to me. Thanks