Does Qt6 built applications run on Windows 7?
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Unfortunately, I have to ensure that my applications work on Windows 7 onwards. If I build an applications using Qt6/Windows 10, does it work on Windows 7? I understand its not officially supported but would like to know if the app would actually work reliably or not?
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It doesn't matter if your build machine is using Windows 10, but to make it work on Windows 7 you have to compile Qt (and your app) using Windows 7 SDK. You'd have to compile Qt yourself using a toolchain configured to use it.
I haven't tried, but I don't think Qt6 would compile with Windows 7 SDK without some serious patching. Certainly not all modules, especially the newer ones. It's in the "try it yourself" territory I guess. Or just keep using Qt5.
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@Taytoo According to https://doc.qt.io/qt-6/supported-platforms.html Windows 7 is not supported by Qt6.
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@hskoglund has made a thread recently - https://forum.qt.io/topic/133002/qt-creator-6-0-1-and-qt-6-2-2-running-on-windows-7/2 - where he made a working back port of Qt6 to windows 7.
That @Taytoo should get you almost all the way there.
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@JonB said in Does Qt6 built applications run on Windows 7?:
@Taytoo
Just throwing my 2 cents in. If you want to keep supporting Win 7, why move to Qt 6 yet and invite grief? Why not stick with safe-and-stable Qt5, at least until need for Win 7 has past?Qt5 does not support OpenSSL 3.x (openssl 1.1.1 will reach end of support next year). Plus, Qt6 has newer features as well.
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@Taytoo said in Does Qt6 built applications run on Windows 7?:
Qt5 does not support OpenSSL 3.x (openssl 1.1.1 will reach end of support next year
And Windows 7 has already past end of support, but that does not deter you :) Did you verify that Win 7 has correct OpenSSL 3.x support? I see some possible bugs reported....
Plus, Qt6 has newer features as well.
Plus newer bugs, and features dropped!
Anyway, point taken, of course I understand you know your needs. It was just a thought.
The post by @J-Hilk refers you to work done by @hskoglund for Win7 Qt6 which you will want to read.
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@J-Hilk said in Does Qt6 built applications run on Windows 7?:
@hskoglund has made a thread recently - https://forum.qt.io/topic/133002/qt-creator-6-0-1-and-qt-6-2-2-running-on-windows-7/2 - where he made a working back port of Qt6 to windows 7.
That @Taytoo should get you almost all the way there.
Actually, I will do the development on Windows 10, just want to make sure that the application/binary compiled using Qt6 framework would run reliably on Windows 7.
Qt6 Supported Platforms page says that the listed platforms are the only ones Qt6 is tested on, so basically they are not testing it on Windows 7 and thus not claiming Win7 is supported. I'm guessing its highly unlikely that any common Qt framework feature would cause crashes etc on Windows 7?
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@Chris-Kawa said in Does Qt6 built applications run on Windows 7?:
It doesn't matter if your build machine is using Windows 10, but to make it work on Windows 7 you have to compile Qt (and your app) using Windows 7 SDK. You'd have to compile Qt yourself using a toolchain configured to use it.
I haven't tried, but I don't think Qt6 would compile with Windows 7 SDK without some serious patching. Certainly not all modules, especially the newer ones. It's in the "try it yourself" territory I guess. Or just keep using Qt5.
I'll be using MSVC 2022 (v143) toolchain, which supports Windows 7 onwards. My dev environment is MSVC 2022 on Windows 10, so don't need to compile/run Qt6 tools on Windows 7 itself, just want my application to work on Windows 7.
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@J-Hilk said in Does Qt6 built applications run on Windows 7?:
@hskoglund has made a thread recently - https://forum.qt.io/topic/133002/qt-creator-6-0-1-and-qt-6-2-2-running-on-windows-7/2 - where he made a working back port of Qt6 to windows 7.
Have you actually looked at this?
Today I spent some time debugging how much trouble it would be to make Qt 6.2.2 run on Windows 7. Turns on there are 3 showstoppers: qt6core.dll, qt6gui.dll and the platforms plugin qwindows.dll. Some hacking/backporting later I had new versions of them.
So this is required for Qt 6 applications, not just Qt6 Creator.... What about Qt 6.3, 6.4, 6.5, ... ?
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@Taytoo you actually didn't bother checking the link provided, or you would know, that you need the windows 7 sdk and compile Qt yourself using that sdk.
Or if reading further in the topic, you would have seen the precompiled back ported Qt6 libs that are working on win 7 that @hskoglund provided
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@Taytoo said:
My dev environment is MSVC 2022 on Windows 10, so don't need to compile/run Qt6 tools on Windows 7 itself, just want my application to work on Windows 7
I wasn't talking about Qt tools (Creator etc.) and neither your dev OS nor MSVC version matters. I was talking about Qt library that your app links to. It uses a bunch of WinAPI calls, which come from Windows SDK, and that needs to be a version targeting Windows 7. It also links to a set of Windows SDK libraries (dlls) that also need to be from the right SDK version. Qt6 is supporting Windows 10 SDK out of the box and that's what the precompiled binaries use, so you have to compile Qt yourself with older Windows 7 SDK. This requires some modifications to the library and backporting, which the topic mentioned by @J-Hilk covers.
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I wasn't talking about Qt tools (Creator etc.) and neither your dev OS nor MSVC version matters. I was talking about Qt library that your app links to. It uses a bunch of WinAPI calls, which come from Windows SDK, and that needs to be a version targeting Windows 7. It also links to a set of Windows SDK libraries (dlls) that also need to be from the right SDK version. Qt6 is supporting Windows 10 SDK out of the box and that's what the precompiled binaries use, so you have to compile Qt yourself with older Windows 7 SDK. This requires some modifications to the library and backporting, which the topic mentioned by @J-Hilk covers.
What if I build Qt from sources using Windows 7 sdk, do I still need to patch the binaries mentioned in the other thread? Shouldn't those libraries be built correctly for windows 7 anyways?
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@Taytoo said in Does Qt6 built applications run on Windows 7?:
do I still need to patch the binaries mentioned in the other thread?
Yes
Shouldn't those libraries be built correctly for windows 7 anyways?
No, since Windows 7 is no longer (officially) supported and they won't run on Win7. Update your OS or stay at Qt5.
