Deploying qt5.2.0: won't find windows platform plugin

Angivare · wrote on 3 Feb 2014, 19:25

Hello, I am trying to deploy an application I wrote with QtCreator 5.2.0, using the MinGW 4.8 compilator.
I compiled it in release mode, but I can't seem to make it work on a machine without Qt installed: I renamed my Qt dir to Qte so it can't find the dll/plugins in there, and my app's folder is like this:

app.exe
other dlls
libEGL.dll
libGLESv2.dll
/platforms/qwindows.dll

Problem is: my app won't just go and grab that qwindows.dll but still tries to get that plugin from my QTDIR/Qt5.2.0/5.2.0/mingw48_32/plugins/platforms and it's giving me error 'This application failed to start because it could not find or load the Qt platform plugin "windows"'

I've searched over google and this forum for 2 days and tried lots of things: qt.conf won't do anything, I've added libEGL.dll and libGLESv2.dll, and qwindows.dll is in the right place, I just can't think of anything else. Another test app just works, but mine doesn't.
If this changes anything, I'm using a few win32 functions to set hooks and get mouse/keyboard inputs even when my widget hasn't got the focus.

sierdzio · wrote on 4 Feb 2014, 08:05

See if you have QTDIR variable set in your environment. Then make sure you've read the whole "deployment guide":http://qt-project.org/doc/qt-5/windows-deployment.html.

Angivare · wrote on 4 Feb 2014, 15:49

My QTDIR variable isn't set, and I have already read (2 times now :c ) that deployment guide

sierdzio · wrote on 5 Feb 2014, 05:23

What happens when you put qwindows.dll in <app dir>/plugins/platforms/qwindows.dll?

Have you run the dependency walker?

Angivare · wrote on 5 Feb 2014, 11:39

putting qwindows.dll in plugins/platforms doesn't change anything, and the dependency walker gives me the following:
http://puu.sh/6KKos.png
Though some of the dlls listed here just aren't installed with windows (it's like, version l-1-1-0 is there but not l-1-1-1)

Well, I eventually moved back to Qt4.8 until this problem is solved.

sierdzio · wrote on 5 Feb 2014, 12:32

What about that IESHIMS.dll there?

Angivare · wrote on 5 Feb 2014, 14:14

I have multiple versions of that DLL in my windows directory, and none of them change anything.

Priya_sipl · wrote on 7 Mar 2014, 11:39

Hi Anglvare,

Try to add <app dir>/platforms/qwindows.dll instead of <app dir>/plugins/platforms/qwindows.dll and in your release
folder add folder platforms/qwindows.dll .

hskoglund · wrote on 7 Mar 2014, 15:25

That directory "QTDIR/Qt5.2.0/5.2.0/mingw48_32/plugins/platforms" is written into your Qt files when you install it. And as you've discovered, it's not so good on another computer :-)

Dependency walker and similar tools are for diagnosing errros with the normal DLLs, but this problem is within Qt itself, when it tries to load its "underbelly" or QPA, i.e. its platform files.

Anyway, there are 3 ways to override/specify where Qt's platform files are located: rewrite that hardwired dir in your app's .exe file, add a QT.CONF file together with your app, or add one line in your app's main.cpp to tell Qt where to find the platform files.

I think option 3 is the easiest, check out "my blog post":http://www.tripleboot.org/?p=138 where I show you how to add one line to your main.cpp and fix this problem.

P.S. I see you've copied only the platforms directory together with the .exe file and the .DLLs. But later on you might need SQLDrivers etc, so I usually copy the whole plugins directory to the target computer. It's a slight waste of harddisk space but much easier to make it work. And then just add that line to your main.cpp and you should be good to go :-)

Priya_sipl · wrote on 7 Mar 2014, 15:45

I tried this but getting the same exception window.

hskoglund · wrote on 7 Mar 2014, 15:48

Hmm... just checking, you copied the plugins directory (not just the platforms) so that it is together with your .exe file and the .dlls?

EDIT: oh I forgot to say. to keep it simple: don't set any QT_DIR or other Qt-flavored environment variables on the target computer. (You can do it but I think it just complicates things.)

JKSH · wrote on 7 Mar 2014, 23:17

[quote]That directory “QTDIR/Qt5.2.0/5.2.0/mingw48_32/plugins/platforms” is written into your Qt files when you install it. And as you’ve discovered, it’s not so good on another computer :-)[/quote]No, Qt also searches your .exe's subfolders too. You do NOT need to modify qt.conf, or set environment variables, or add code to main.cpp.

You just need to copy the files into the correct subfolders. Simple guide here: http://qt-project.org/wiki/Deploy_an_Application_on_Windows

Example:
!http://i.imgur.com/S582DlV.png(DLL paths)!

hskoglund · wrote on 7 Mar 2014, 23:43

Yes, you're right, I tested with a barebones HelloQt (with no extra line in main.cpp!) and it worked when I copied it to another computer, set up as in your guide, specifically putting the platforms directory next to the .exe file. Good!
I think I'll update my blog post!

JKSH · wrote on 7 Mar 2014, 23:56

Glad I could help. :) Thank you for blogging about Qt and for helping others use Qt!

hskoglund · wrote on 8 Mar 2014, 00:02

Thanks!
I'm used to pay money to Microsoft for new Visual Studio releases, but now when I've switched to Qt and can download it for free, I figured blogging etc. is another way to pay.

This infamous issue about not finding the windows plugin, it is a challenge to communicate to new users I think. Maybe for the next Qt conference, you can make T-shirts with that dialog box on them :-)

Priya_sipl · wrote on 10 Mar 2014, 07:34

Thank you JKSH and hskoglund
I tried the same and it worked.

I was facing problem when i was creating the setup for windows using Inno compiler.

When I was including platform dlls with its folder, it didn't include platform folder but instead directly copied qwindows.dll to the installed folder.

In Inno scripts, it was mentioned like this:

Source: "C:\MyQtApp\release\platforms*"; DestDir: "{app}"; Flags: ignoreversion

So I added "platforms" manually so that on installation all platform dll would be copied to platform folder.

Source: "C:\MyQtApp\release\platforms*"; DestDir: "{app}\platforms"; Flags: ignoreversion

hskoglund · wrote on 10 Mar 2014, 08:14

Good!

BTW, I've updated "my blog post":http://www.tripleboot.org/?p=138 about deploying Qt now, so it's really fancy :-)

geoniko · wrote on 29 May 2014, 08:17

"That directory “QTDIR/Qt5.2.0/5.2.0/mingw48_32/plugins/platforms” is written into your Qt files when you install it"

Can you be more specific? Where exactly is it written too? I need to build x64 windows version of Qt 5.3 for VS2012 (which is not available for download). It would be good to set this correctly so that at least for developers it will work...

Thanks for any advice...

Priya_sipl · wrote on 29 May 2014, 08:26

Hello Geonlko,

“That directory “QTDIR/Qt5.2.0/5.2.0/mingw48_32/plugins/platforms” is written into your Qt files when you install it” means

When we install qt (in this it is Qt5.2.0 mingw 32 bit version) in our system,
all packages get installed with it.

In that packages you will find platform folder that has platform specific dlls.

These are required when we build setup for our Qt application.

For Qt 5.3 64 bit version, you have to go for VS2013, it is available

JKSH · wrote on 29 May 2014, 08:54

[quote author="geoniko" date="1401351479"]"That directory “QTDIR/Qt5.2.0/5.2.0/mingw48_32/plugins/platforms” is written into your Qt files when you install it"

Can you be more specific? Where exactly is it written too?[/quote]They are written inside the DLLs themselves.

In hindsight, that's a poor decision because it prevents people from moving their Qt installation to a different folders, but changing this behaviour isn't high on the priority list.

[quote]I need to build x64 windows version of Qt 5.3 for VS2012 (which is not available for download). It would be good to set this correctly so that at least for developers it will work...[/quote]When you run configure.bat, set the -prefix option to the path where you want to install Qt.

Then, make sure that your Qt libraries are located in this exact path on each of your developers' machines.