Known Issues or Limitations

The following is a list of known issues in Qt for MCUs 1.7. For workarounds or information about the status of these issues, contact Qt Support.

To view all user-reported issues, visit the Qt for MCUs public bug tracker.


  • Development host environment support is limited to Windows 10.

Qt Quick Ultralite

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

      A version number can optionally be added but is not strictly required in Qt Quick Ultralite.

    • Unknown component for ColorizedImage and StaticText

      Set the QML_IMPORT_PATH variable in your CMake project file to the location of the QUL compatibility module to solve this issue.

  • QML debugging is not supported
  • QML profiling is not supported

Qt Design Studio

  • On-device preview is not supported. To preview the design on your MCU board, use the auto-generated CMake project and compile it using Qt Creator.
  • Qt Quick Ultralite-specific QML types (StaticText, ColorizedImage) are not available in the component library.

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 1.7 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.
  • The Monotype Spark font engine (Technology Preview) is not supported.


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

  • Screen may flicker while performing 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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