Qt version for qgroundcontrol 4.2.3

Which qt version should I use to develop qgroundcontrol 4.2.3?

yeah i found it. 5.15 qt version

is there any way to run QGC on a 32bit computer. That’s all I have!

they say ‘’ Prebuilt QGroundControl versions from 4.0 onwards are 64-bit only. It is possible to manually build 32 bit versions (this is not supported by the dev team)…‘’
Since it is an open source software, if you can download the files and export them as 32 bit in qt creator, your problem may be solved. But I don’t know much.

How did you found that correnct version of QT?
By yourself with google?
By help of another people?

Maybe a good start is to look at the CI builds which run on github. Here: qgroundcontrol/macos_release.yml at master · mavlink/qgroundcontrol · GitHub you can see which version is used for the CI build.