Qt for Android known issues

Qt for Android known issues

• Qt 5.15.0 QDir doesn't support path with "content" scheme, when working with directories in file dialogs use QFileDialog::DontUseNativeDialog to get a "file" scheme path instead.
• In order to work with Qt 5.14.0 and later releases, the AndroidManifest.xml generated for older versions has to be updated. This can be done either by replacing the manifest automatically using Qt Creator, or by manually editing the manifest. An example of the modifications needed can be found in https://codereview.qt-project.org/c/qt/qtandroidextras/+/278987
• With Qt 5.14.0, unfortunately, release packages of Qt Quick applications will be missing integral files by default, and thus they will crash on startup. You can work around this by disabling the Qt Quick Compiler in the build settings of the project (Projects -> Build Settings -> qmake -> Enable Qt Quick Compiler). See QTBUG-80713 for more details.
• Qt 5.14.0: The devicePixelRatio scale factor will be rounded to an integer when setting the Qt::EnableHighDpiScaling attribute, unlike previous behavior on Android where the devicePixelRatio was not rounded. As a workaround, call QGuiApplication::setHighDpiScaleFactorRoundingPolicy(Qt::HighDpiScaleFactorRoundingPolicy::PassThrough) at application to disable rounding. Qt 5.14.1 will make PassThrough the default on Android and restore the previous behavior.
• If you encounter the error "ld: error: cannot find -lc++" when using Android NDK r20, please install Android NDK r19 instead. This issue has been fixed in upcoming Qt versions. See https://bugreports.qt.io/browse/QTBUG-76293 for more information, as well as a way to temporarily work around the issue in your project settings.
• The Android SDK tools do not work together with Oracle's JDK 9 on Windows. If Qt Creator says your SDK is missing the SDK platform, or if you see errors such as "Android build SDK not defined. Check Android settings." when building a project, install a JDK 8 or earlier.
• Windows has a limitation on path lengths which can cause problems when your project is installed into a location with a very long path name (260 characters or more). This can be the cause of:
  • FileNotFoundException in openAsset() on the startup of your application, try moving it to a directory with a shorter path.
  • "java.io.IOException: com.android.ide.common.process.ProcessException: Error while executing process D:\Android\Sdk\build-tools\29.0.0\aidl.exe with arguments [...]".
• By default, the Back key will terminate Qt for Android apps, unless the key event is accepted. Unfortunately, due to misleading documentation (QTBUG-35155), many applications (including Qt examples) are incorrect and will block the back key. We recommend making the logic explicit: always accept() the Key_Back event, and quit() the application explicitly if required.

Issues with older versions

• When running an application for arm64-v8a from Qt Creator, you may encounter the error "clang++.exe: error: no such file or directory: '/path/to/ndk/sources/cxx-stl/llvm-libc++/libs/arm64-v8a/libc++.so.16'". This can be worked around by editing the built environment in the project settings and changing the environment variable ANDROID_NDK_PLATFORM to "android-21"
• There is a bug in GCC in the latest Android NDK, making it impossible to use it for building Qt. For Qt 5.12, the clang toolchain should be used and is used by the official binary packages. For older versions, please use Android NDK r10e, which does not have the relevant GCC bug. NDK r15 produces applications that fail with the error message 'This application failed to start because it could not find or load the Qt platform plugin "android"'. See also the bug report.
• The Android NDK compiler has a bug when building for armv5 and deploying on older kernels. This will cause Qt applications to crash on startup. When building Qt, you need to disable 64-bit atomics for armv5. See QTBUG-52923 for more information.
• Qt Quick 1 apps must be deployed using qrc (QTBUG-32170)
• The Qt Multimedia Widgets module is not supported on Android, which means video display is only available using the VideoOutput and Video QML items.
• On Kindle Fire 1st generation, there is a limitation on the number of libraries that can be loaded which will lead to shader compilation errors when running some Qt Quick apps. Apps that exhibit this bug will be rejected from being published to the Amazon market. A work-around for the issue is to reduce the number of libraries that are loaded, e.g. by deleting some image format plugins that are not required. See QTBUG-33264 for more information.
• With the first edition of Samsung XCover 3 (SM-G388F), there appears to be an issue with the graphics driver, causing Qt applications to crash when they are resumed after being suspended. The current investigation points towards a threading issue in the software on the device itself. The issue does not occur with the second edition of the same device, SM-G389F. There is no known workaround for this at the moment, so the recommendation is to blacklist this particular device model in Google Play. Setting the QML_BAD_GUI_RENDER_LOOP environment variable to 1 will make the crash less likely to occur. QTBUG-55392
• There are issues with the updated Android SDK which makes it impossible to use it together with earlier versions of Qt for Android. This has been fixed in Qt 5.9.0, but for older versions, it is possible to use the following links to download a working version of the SDK (do not update the SDK after downloading): macOS Windows and Linux.