Qt5 platforms plugins ?



  • Where I should place the qwindows.dll or qwindowsd.dll ? Because as you mentioned in "Failed to load platform plugin.":http://qt-project.org/forums/viewthread/23367 it should be in platforms directory, but it did not help me. Thanks for answers...


  • Moderators

    [quote author="Peppy" date="1358024644"]Where I should place the qwindows.dll or qwindowsd.dll ? Because as you mentioned in "Failed to load platform plugin.":http://qt-project.org/forums/viewthread/23367 it should be in platforms directory, but it did not help me. Thanks for answers...[/quote]It should work if the platforms directory is in the same directory as your executable:

    C:\MyApp\myapp.exe
    C:\MyApp\platforms\qwindows.dll

    When you said "It did not help me", what was the issue? What error message did you get?



  • @
    Debug Error
    ...
    Failed to load ... Available platforms are:
    windows
    minimal
    windows
    minimal

    Press retry...
    @

    Well, this copying did not help me at all. (Nothing has changed)...


  • Moderators

    Very strange. Some questions:

    I presume it says Failed to load platform plugin "windows"., and not another plugin; is that correct?

    What's your OS? What many bits?

    Did you download the precompiled Qt 5.0.0, or build it yourself?

    Is Qt 5 in your PATH?

    Did you copy the other DLLs (e.g. Qt5Core.dll) into your application folder?



  • I have the same problem "here":http://qt-project.org/forums/viewthread/23658/
    If somebody manages to make it work "outside" Qt Creator, it will also be a big help to me.


  • Moderators

    Try temporarily changing the name of your top-level Qt folder (i.e. the place where you installed/built Qt) -- do any other error messages appear when you try to run your app outside Qt Creator?



  • [quote author="JKSH" date="1358040589"]Very strange. Some questions:

    I presume it says Failed to load platform plugin "windows"., and not another plugin; is that correct?

    What's your OS? What many bits?

    Did you download the precompiled Qt 5.0.0, or build it yourself?

    Is Qt 5 in your PATH?

    Did you copy the other DLLs (e.g. Qt5Core.dll) into your application folder?[/quote]

    "windows" and "minimal"

    Windows 7 32 bits

    Built it myself - VS 2012

    NOT in the PATH (I think Qt Creator just sets the path for itself)

    Included are libGLESv2.dll, Qt5Core.dll, Qt5Gui, Qt5Widgets, paltforms(qwindows.dll, qminimal.dll)

    [quote author="JKSH" date="1358040890"]Try temporarily changing the name of your top-level Qt folder (i.e. the place where you installed/built Qt) -- do any other error messages appear when you try to run your app outside Qt Creator?[/quote]

    same results...


  • Moderators

    Strange indeed. It looks like it's finding multiple versions of the same plugin and tries to load the wrong one.
    Kind of a brute force approach but maybe try to find all qwindows.dll files on your machine, temporarily move or rename them leaving only the MyApp\platforms\qwindows.dll and see what happens.



  • actually I only have one msvc2012 build (which I build myself) of Qt5

    ...I also installed the Qt 5.0.0 VS2010 downloadable here which I think will be of no effect since they are of different VS variant. No other Qt5 on my machine.

    Are there any other "hidden" parameters or settings done by Qt Creator before running an app within it? App works when creator is used though.


  • Moderators

    [quote author="Code_ReaQtor" date="1358078242"]which I think will be of no effect since they are of different VS variant.[/quote]
    This may actually be the problem.
    If your (VS2012) app picks up VS2010 plugins they might be recognized but fail to load. Make tripple sure you didn't mix the dlls and that none of the qt dlls are seen system-wide (like in the PATH or placed in some system directory).



  • [quote author="Krzysztof Kawa" date="1358078537"]
    If your (VS2012) app picks up VS2010 plugins they might be recognized but fail to load. Make tripple sure you didn't mix the dlls and that none of the qt dlls are seen system-wide (like in the PATH or placed in some system directory).
    [/quote]

    I make sure no Qt stuffs were included in my PATH. It is a bad habit to do that.


  • Moderators

    It MIGHT be an issue with your VS 2012 build. I don't have VS 2012 installed, so I can't investigate for you, sorry. Are you willing to try a VS 2010 build (or "MinGW":http://qt-project.org/forums/viewthread/23002/), and see if that works?


  • Moderators

    I've got exactly the same setup here: VS2010 from Qt download pages and personally compiled VS2012 version, but everything seems to work out of the box.

    Another thing to try would be to use Profiling option in Dependency Walker. In the profiling window you can select "Use full paths when logging file names". The output is somewhat messy but you can use find(ctrl+f) to find qwindows.dll and other modules and check from what path they are actually loaded and why are they doubled.



  • @JKSH
    Can't do with VS2010, I have problems installing VS2010 in my computer since it won't compile even an ordinary VS2010 app. Got errors like "oldnames.lib" something errors. Found out header files weren't installed. Tried and tried but never solved it ... even the M$ forum can't help... so I removed it. Only have VS2008 and VS2012 on my machine.

    But for the mingw, I think I will take a look at that since mingw is ok with my machine. Thanks

    @Krzysztof
    I will recheck dependency walker. Thanks



  • Did you set QT_PLUGIN_PATH environment variable ?



  • [quote author="soroush" date="1358092375"]Did you set QT_PLUGIN_PATH environment variable ? [/quote]

    NO....



  • Well, in my case, I have been using only the correct libraries, whether I have been building Qt (MSVC 2012) or using downloaded installation of Qt (MSVC 2010).

    I dont have Qt in PATH. Seems like to be a very strange DLL Hell problem...



  • [quote author="JKSH" date="1358040589"]Very strange. Some questions:

    I presume it says Failed to load platform plugin "windows"., and not another plugin; is that correct?

    What's your OS? What many bits?

    Did you download the precompiled Qt 5.0.0, or build it yourself?

    Is Qt 5 in your PATH?

    Did you copy the other DLLs (e.g. Qt5Core.dll) into your application folder?[/quote]

    Yes you are right. But it says that plugins are available... I really dont understand what is going on...

    • Windows 7 Professional x64 bit.
    • I have been using both of them but not at once.
    • Qt is not in my environment
    • Yes, I did.

  • Moderators

    I'm quite lost here, to be honest. :-/

    Try running your program from within CDB -- it will show you a list of DLLs that are being loaded, and it just might provide a clue.



  • Well, I have dumped the library paths but the only one was:
    @C:/Qt/5.0.0/msvc2010/plugins@

    What makes no sense...

    When I run it from QtCreator, it works, but not as a stand-alone...



  • Well, I have found solution in copying also libEGL.dll or libEGLd.dll (depends on what type of building do you run!) into the root application library...what a freaking mistake!

    Thanks to: http://qt-project.org/forums/viewthread/21269



  • [quote author="Peppy" date="1358179576"]Well, I have found solution in copying also libEGL.dll or libEGLd.dll (depends on what type of building do you run!) into the root application library...what a freaking mistake!

    Thanks to: http://qt-project.org/forums/viewthread/21269[/quote]

    Wow! Mine worked too! Thanks



  • Solved it for me as well.



  • Just wanted to say I had this issue as well. Solve for me. Found through google so I figured I'd bump it.



  • copy the qwindows.dll from qtdir/plugins/platform to your application_directory/platform and voila it solves the problem.



  • Adding libEGL.dll worked for me too. Was long for me to find the solution so I figured I'd bump it too.



  • I was getting that exact same "failed to load" error, however, I didn't compile my own binaries - I used the ones from the softwareforge project qt-x64 : http://sourceforge.net/projects/qtx64/ .

    It turns out that they bundle a utility in there called qtbinpatcher.exe that patches the binaries where the paths have been hardcoded in. Once I ran that everything worked.

    Is it just me, or does hardcoding an absolute path into the binaries like that seem like horrible idea? What were they thinking?


  • Moderators

    [quote author="Ph0t0n" date="1392352947"]I was getting that exact same "failed to load" error, however, I didn't compile my own binaries - I used the ones from the softwareforge project qt-x64 : http://sourceforge.net/projects/qtx64/ .

    It turns out that they bundle a utility in there called qtbinpatcher.exe that patches the binaries where the paths have been hardcoded in. Once I ran that everything worked.

    Is it just me, or does hardcoding an absolute path into the binaries like that seem like horrible idea? What were they thinking?[/quote]I agree that it is a horrible idea. Unfortunately, it's not something that's easy to undo -- so we'll have to deal with it for now.

    Anyway, welcome to the Qt Dev Net! I'm glad you found a solution to your problem. Thank you for sharing your solution.


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