How to run a Qt Program without Qt itself being installed?

Question

I have written a program with Qt5.3.1 and run it on my development machine where it works fine. I copied all necessary .dll files into the folder where my .exe is. These are:

• Qt5Widgets.dll
• Qt5Network.dll
• Qt5Gui.dll
• Qt5Core.dll
• icudt51.dll
• icuin51.dll
• icuuc51.dll
• libgcc_s_dw2-1.dll
• libwinpthread-1.dll
• libstdc++-6.dll

Now I want to run that program on a machine that has no Qt installed. How do I do that? It shouldn't be necessary for users to install an IDE just to use a program, right?

Details of the development machine where it works:

• Windows 8
• Qt 5.3.1

The deploying platform is:

• Windows Vista
• No Qt installed but all necessary .dlls are in place

Errors I get are first:

This application failed to start because it could not find or load the Qt platform plugin "windows". Reinstalling the application may fix this problem.

Next error message is:

This application requested the Runtime to terminate in an unusual way. Please contact support.

Then the program crashes. But if I install Qt5.3.1 it works. So it has something to do with files in the c:/Qt directory

Solution 1

A better solution is to use the Qt SDK application "windeployqt". It is used to copy all the required dlls and plugins to your application folder based on target platform. You can then run that on another computer. Here is the documentation: https://doc.qt.io/Qt-5/windows-deployment.html.

For example, if your executable was built using mingw53_32 and your executable is in "C:\example_qtapp":

QT_INSTALL_DIR\minqw53_32\bin\windeployqt.exe c:\example_qtapp

Solution 2

This application failed to start because it could not find or load the Qt platform plugin "windows".

For this problem, you should copy the plugin {QTSDK}/plugins/platforms/qwindows.dll to {YOUR_EXE_DIR}/platforms/qwindows.dll.

Solution 3

The short answer is you either need to do a static build, or you need to redistribute the Qt shared library DLLs. If you're looking for a smaller file size static builds are often better, but there may be legal implications with this approach if you're using Qt5 under a LGPL license. I'm not a lawyer, but you can read about LGPL linking rules in LGPL section 4.1.

The long answer is you should read the general Qt5 deployment guide and the Qt5 for Windows deployment guide. These go into quite a bit of detail.

Solution 4

I have encountered this problem as well,

In your Qt Directory, with the proper Qt version C:\Qt\Qt5.2.1\5.2.1\mingw48_32\plugins\platforms\

copy qwindows.dll into a new folder that lives next to your executable, such that your list would be

• Qt5Widgets.dll
• Qt5Network.dll
• Qt5Gui.dll
• Qt5Core.dll
• icudt51.dll
• icuin51.dll
• icuuc51.dll
• libgcc_s_dw2-1.dll
• libwinpthread-1.dll
• libstdc++-6.dll
• platforms/qwindows.dll

Solution 5

You should place Qt DLLs along the release version of your executable. These are Qt5Core.dll, Qt5Gui.dll and possibly the ones for other modules that you have used. These dll files are in your installed Qt Directory in bin folder. You should also place LIBGCC_S_DW2-1.DLL, MINGWM10.DLL and LIBSTDC++-6.dll in case you are using MinGW.

If you are using plugins you should place their dll in a folder named plugins beside your exe. In case of using icons and images you should ship their dlls like qico.dll and qsvg.dll in a folder named imageformats.

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