Maybe my earlier email was not explicit or detailed enough. The "aptitude update" I referred to, performed on 2026-10-06, updated the qt6 packages but not flightgear. This caused the flightgear launcher to stop working and instead show a blank page and an error message box as described.
I resorted to passing all parameters to fgfs on the command line to select aircraft, airport, aircraft and TerraSync directories etc. Only the launcher is affected. Finally, I have been able to find qml6-module-qt-labs-assetdownloader again and reinstall it but this did not repair the FlightGear launcher. Here is the complete log for the update performed by aptitude. flightgear is notably absent and its launcher worked without a problem before the update. The Qt6 packages are primary suspects. [REMOVE, NOT USED] libavformat62:amd64 7:8.1.2-2+b3 [REMOVE, NOT USED] libbotan-3-12:amd64 3.12.0+dfsg-2 [REMOVE, NOT USED] libswscale9:amd64 7:8.1.2-2+b3 [REMOVE, NOT USED] qml6-module-qt-labs-assetdownloader:amd64 6.10.2+dfsg-6 [INSTALL, DEPENDENCIES] libbotan-3-13:amd64 3.13.0+dfsg-2 [INSTALL, DEPENDENCIES] libopenh264-8:amd64 2.6.0+dfsg-2+b2 [INSTALL, DEPENDENCIES] libqt6labsstylekit6:amd64 6.11.2+dfsg-3 [INSTALL, DEPENDENCIES] qml6-module-qt-labs-stylekit:amd64 6.11.2+dfsg-3 [UPGRADE] assistant-qt6:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] coinor-libcgl1:amd64 0.60.9+ds-1+b2 -> 0.60.10+ds-1 [UPGRADE] designer-qt6:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] dsda-doom:amd64 0.29.4+dfsg-4 -> 0.30.0+dfsg-1 [UPGRADE] fonts-gamaliel:amd64 0.1-3 -> 0.1+ds-1 [UPGRADE] graphviz:amd64 14.1.2-1+b3 -> 14.1.2-1+b4 [UPGRADE] gstreamer1.0-plugins-good:amd64 1.28.7-1 -> 1.28.7-1+b1 [UPGRADE] gtk-update-icon-cache:amd64 4.22.4+ds-1 -> 4.24.0+ds-2 [UPGRADE] libbotan-3-dev:amd64 3.12.0+dfsg-2 -> 3.13.0+dfsg-2 [UPGRADE] libcdt6:amd64 14.1.2-1+b3 -> 14.1.2-1+b4 [UPGRADE] libcgraph8:amd64 14.1.2-1+b3 -> 14.1.2-1+b4 [UPGRADE] libdbus-glib-1-2:amd64 0.114-2+b1 -> 0.116-1 [UPGRADE] libdbus-glib-1-dev:amd64 0.114-2+b1 -> 0.116-1 [UPGRADE] libdbus-glib-1-dev-bin:amd64 0.114-2+b1 -> 0.116-1 [UPGRADE] libgpgmepp7:amd64 2.1.0-2 -> 2.2.0-2 [UPGRADE] libgtk-4-1:amd64 4.22.4+ds-1 -> 4.24.0+ds-2 [UPGRADE] libgtk-4-bin:amd64 4.22.4+ds-1 -> 4.24.0+ds-2 [UPGRADE] libgtk-4-common:amd64 4.22.4+ds-1 -> 4.24.0+ds-2 [UPGRADE] libgvc7:amd64 14.1.2-1+b3 -> 14.1.2-1+b4 [UPGRADE] libgvplugin-gd8:amd64 14.1.2-1+b3 -> 14.1.2-1+b4 [UPGRADE] libgvplugin-pango8:amd64 14.1.2-1+b3 -> 14.1.2-1+b4 [UPGRADE] libgvpr2:amd64 14.1.2-1+b3 -> 14.1.2-1+b4 [UPGRADE] libmd0:amd64 1.2.0-2 -> 1.3.0-1 [UPGRADE] libpathplan4:amd64 14.1.2-1+b3 -> 14.1.2-1+b4 [UPGRADE] libqt6concurrent6:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] libqt6core6t64:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] libqt6dbus6:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] libqt6designer6:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] libqt6designercomponents6:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] libqt6gui6:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] libqt6help6:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] libqt6httpserver6:amd64 6.10.2-6 -> 6.11.2-2 [UPGRADE] libqt6labsplatform6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6labssynchronizer6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6multimedia6:amd64 6.10.2-6 -> 6.11.2-3 [UPGRADE] libqt6multimediawidgets6:amd64 6.10.2-6 -> 6.11.2-3 [UPGRADE] libqt6network6:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] libqt6opengl6:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] libqt6openglwidgets6:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] libqt6pdf6:amd64 6.10.2+dfsg-5 -> 6.11.2+dfsg-4 [UPGRADE] libqt6pdfquick6:amd64 6.10.2+dfsg-5 -> 6.11.2+dfsg-4 [UPGRADE] libqt6pdfwidgets6:amd64 6.10.2+dfsg-5 -> 6.11.2+dfsg-4 [UPGRADE] libqt6positioning6:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] libqt6positioning6-plugins:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] libqt6positioningquick6:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] libqt6printsupport6:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] libqt6qml6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6qmlcompiler6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6qmlmeta6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6qmlmodels6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6qmlnetwork6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6qmlworkerscript6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6quick3d6:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] libqt6quick3dassetimport6:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] libqt6quick3dassetutils6:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] libqt6quick3dglslparser6:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] libqt6quick3diblbaker6:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] libqt6quick3dphysics6:amd64 6.10.2-5 -> 6.11.2-2 [UPGRADE] libqt6quick3druntimerender6:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] libqt6quick3dutils6:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] libqt6quick3dxr6:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] libqt6quick6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6quickcontrols2-6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6quickshapes6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6quickshapesdesignhelpers6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6quicktemplates2-6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6quicktest6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6quickvectorimage6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6quickvectorimagegenerator6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6quickvectorimagehelpers6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6quickwidgets6:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] libqt6scxml6:amd64 6.10.2-4 -> 6.11.2-2 [UPGRADE] libqt6scxml6-bin:amd64 6.10.2-4 -> 6.11.2-2 [UPGRADE] libqt6serialport6:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] libqt6shadertools6:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] libqt6spatialaudio6:amd64 6.10.2-6 -> 6.11.2-3 [UPGRADE] libqt6sql6:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] libqt6sql6-sqlite:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] libqt6statemachine6:amd64 6.10.2-4 -> 6.11.2-2 [UPGRADE] libqt6svg6:amd64 6.10.2-9 -> 6.11.2-2 [UPGRADE] libqt6svgwidgets6:amd64 6.10.2-9 -> 6.11.2-2 [UPGRADE] libqt6test6:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] libqt6uitools6:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] libqt6waylandclient6:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] libqt6webchannel6:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] libqt6webchannelquick6:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] libqt6webengine6-data:amd64 6.10.2+dfsg-5 -> 6.11.2+dfsg-4 [UPGRADE] libqt6webenginecore6:amd64 6.10.2+dfsg-5 -> 6.11.2+dfsg-4 [UPGRADE] libqt6webenginecore6-bin:amd64 6.10.2+dfsg-5 -> 6.11.2+dfsg-4 [UPGRADE] libqt6webenginequick6:amd64 6.10.2+dfsg-5 -> 6.11.2+dfsg-4 [UPGRADE] libqt6webenginewidgets6:amd64 6.10.2+dfsg-5 -> 6.11.2+dfsg-4 [UPGRADE] libqt6websockets6:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] libqt6widgets6:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] libqt6wlshellintegration6:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] libqt6xml6:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] libxdot4:amd64 14.1.2-1+b3 -> 14.1.2-1+b4 [UPGRADE] libxs-parse-keyword-perl:amd64 0.49-1+b1 -> 0.51-1 [UPGRADE] linguist-qt6:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] python3-more-itertools:amd64 11.1.0-2 -> 11.1.0-3 [UPGRADE] qdbus-qt6:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] qdoc-qt6:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] qmake6:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] qmake6-bin:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] qml6-module-qml:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qmltime:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qt-labs-animation:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qt-labs-folderlistmodel:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qt-labs-platform:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qt-labs-qmlmodels:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qt-labs-settings:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qt-labs-sharedimage:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qt-labs-synchronizer:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qt-labs-wavefrontmesh:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtcore:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtmultimedia:amd64 6.10.2-6 -> 6.11.2-3 [UPGRADE] qml6-module-qtnetwork:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtpositioning:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] qml6-module-qtqml:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtqml-models:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtqml-statemachine:amd64 6.10.2-4 -> 6.11.2-2 [UPGRADE] qml6-module-qtqml-workerscript:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtqml-xmllistmodel:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtquick:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtquick-controls:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtquick-dialogs:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtquick-effects:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtquick-layouts:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtquick-localstorage:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtquick-particles:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtquick-pdf:amd64 6.10.2+dfsg-5 -> 6.11.2+dfsg-4 [UPGRADE] qml6-module-qtquick-shapes:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtquick-shapes-designhelpers:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtquick-templates:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtquick-timeline:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] qml6-module-qtquick-tooling:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtquick-vectorimage:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtquick-vectorimage-helpers:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtquick-window:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtquick3d:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] qml6-module-qtquick3d-assetutils:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] qml6-module-qtquick3d-effects:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] qml6-module-qtquick3d-helpers:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] qml6-module-qtquick3d-lightmapviewer:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] qml6-module-qtquick3d-materialeditor:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] qml6-module-qtquick3d-particleeffects:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] qml6-module-qtquick3d-particles3d:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] qml6-module-qtquick3d-physics:amd64 6.10.2-5 -> 6.11.2-2 [UPGRADE] qml6-module-qtquick3d-spatialaudio:amd64 6.10.2-6 -> 6.11.2-3 [UPGRADE] qml6-module-qtquick3d-xr:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] qml6-module-qtscxml:amd64 6.10.2-4 -> 6.11.2-2 [UPGRADE] qml6-module-qttest:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qml6-module-qtwebchannel:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] qml6-module-qtwebengine:amd64 6.10.2+dfsg-5 -> 6.11.2+dfsg-4 [UPGRADE] qml6-module-qtwebengine-controlsdelegates:amd64 6.10.2+dfsg-5 -> 6.11.2+dfsg-4 [UPGRADE] qml6-module-qtwebsockets:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] qt6-base-dev:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] qt6-base-dev-tools:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] qt6-declarative-dev:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qt6-declarative-dev-tools:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qt6-documentation-tools:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] qt6-httpserver-dev:amd64 6.10.2-6 -> 6.11.2-2 [UPGRADE] qt6-image-formats-plugin-pdf:amd64 6.10.2+dfsg-5 -> 6.11.2+dfsg-4 [UPGRADE] qt6-l10n-tools:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] qt6-multimedia-dev:amd64 6.10.2-6 -> 6.11.2-3 [UPGRADE] qt6-pdf-dev:amd64 6.10.2+dfsg-5 -> 6.11.2+dfsg-4 [UPGRADE] qt6-positioning-dev:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] qt6-qmllint-plugins:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qt6-qmlls-plugins:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qt6-qmltooling-plugins:amd64 6.10.2+dfsg-6 -> 6.11.2+dfsg-3 [UPGRADE] qt6-qmltooling-quick3dprofiler-plugin:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] qt6-qpa-plugins:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] qt6-quick3d-assetimporters-plugin:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] qt6-quick3d-dev:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] qt6-quick3d-dev-tools:amd64 6.10.2-3 -> 6.11.2-3 [UPGRADE] qt6-quick3dphysics-dev:amd64 6.10.2-5 -> 6.11.2-2 [UPGRADE] qt6-scxml-dev:amd64 6.10.2-4 -> 6.11.2-2 [UPGRADE] qt6-shader-baker:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] qt6-shadertools-dev:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] qt6-svg-dev:amd64 6.10.2-9 -> 6.11.2-2 [UPGRADE] qt6-svg-plugins:amd64 6.10.2-9 -> 6.11.2-2 [UPGRADE] qt6-tools-dev:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] qt6-tools-dev-tools:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] qt6-webchannel-dev:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] qt6-webengine-dev:amd64 6.10.2+dfsg-5 -> 6.11.2+dfsg-4 [UPGRADE] qt6-webengine-dev-tools:amd64 6.10.2+dfsg-5 -> 6.11.2+dfsg-4 [UPGRADE] qt6-websockets-dev:amd64 6.10.2-3 -> 6.11.2-2 [UPGRADE] qtpaths6:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] qtpaths6-bin:amd64 6.10.2+dfsg-16 -> 6.11.2+dfsg-5 [UPGRADE] wdiff:amd64 1.2.2-9 -> 1.2.3-1 -- Ludovic Brenta.
