Known Issues or Limitations

The following is a list of known issues in Qt for MCUs dev. For workarounds or information about the status of these issues in future versions, please contact Qt Support.


  • Development host environment support is limited to Windows 10.

Qt Quick Ultralite

  • Limited set of Qt Quick Controls are available with Qt Quick Ultralite dev. Refer to Qt Quick Controls support in Qt Quick Ultralite, for an overview about the supported controls.
  • EventLoop:postEvent is not interrupt safe
  • Animation on anchors is not supported.
  • Charts can be drawn only to RGB32 or ARGB32 surface.
  • C++ compilation fails for Text with huge font.pixelSize.
  • Text type does not properly render unicode sequences that require complex text layout. Use StaticText for complex text.
  • In some cases, the Component.completed signal might be triggered for a child element first, before its root or parent element.
  • SequentialAnimation and ParallelAnimation do not start automatically when assigned to a property with the "on" syntax.
  • Setting Item::visible does not change the visible property of child items.
  • Text::font.pointSize does not respect screen dpi. Prefer Text::font.pixelSize.
  • The default state does not persist runtime changes. When changing back to the default state, the initial state is restored.
  • States where multiple PropertyChanges or AnchorChanges target anchor properties on the same item will not work as expected. Use a single PropertyChanges instead.
  • Setting anchors to undefined does not restore previous position and size bindings.
  • A RotationAnimation in a transition may apply to non-rotation properties. Use PropertyAnimation::properties instead.
  • Unqualified model role access without corresponding required property is not supported. See Role access.
  • Shear transforms are not supported.
  • All delegates in a ListView must have the same size, and the size must be explicitly specified.

Qt Creator

  • When editing Qt Quick Ultralite QML files, the following errors are displayed in the Issues panel and highlighted in the code editor. They can safely be ignored:
    • package import requires a version number
    • QML module not found for QtQuick.Templates
    • Unknown component for ColorizedImage and StaticText
  • Qml debugging is not supported
  • Qml profiler is not supported

Qt Design Studio

  • Although all QML types are available, there is no possibility of on-device preview directly from Qt Design Studio. To preview the design on MCU boards, the project must be converted to a CMake project and compiled from Qt Creator.
  • Qt Quick Ultralite-specific QML types (StaticText, ColorizedImage) are not available
  • The property editor does not take into account the limited available APIs in Qt Quick Ultralite
  • The timeline feature is not supported on MCUs

Renesas RH850

The following is a list of known issues on the Renesas RH850 hardware.

  • The internal ROM is used to store code (data and text) and the graphical assets only. This limits the size of the executable to be not more than 5 MB.
  • Qt Quick Ultralite dev does not enter low CPU power mode. If no frame is rendered and no other tasks are running, Qt Quick Ultralite loops until next frame needs to be rendered or another task needs CPU time.
  • Only bare metal is supported.


The following is a list of known issues on the STM32H750B hardware.

  • Screen may flicker when performing some double precision operations. For that reason, qreal defaults to float instead of double
  • The SDK version 1.6.0 is not supported yet.

NXP i.MXRT1050 and NXP i.MXRT1064

The following is a list of known issues on the NXP i.MXRT1050 hardware.

  • When debugging, interrupted program won't resume its execution and must be restarted by using the mon reset halt command.


  • To work around a GNU Arm Embedded Toolchain bug (https://bugs.launchpad.net/gcc-arm-embedded/+bug/1747966), all the object files and libraries are passed to ld in a linker group (using --start-group/--end-group). Additionally, libraries are passed to linker before application object files, which is opposite to default behavior.

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