This applications failed to start because it could not find or load The Qt platform plugin "window".

  • I 'm trying to make a 'package' (=put all files needed) for deploying my application (made wit Qt Creator 5.2.1 MSVC2010 in Win XP).
    I used windeployqt.exe (from directory G:\Qt\Qt5.2.1\5.2.1\msvc2010\bin) which picked up some files, but, I guess, not all of them.
    In my development partition (I have a partition with Win XP and a partition with Win 7), that is in Win XP, works fine.
    But when I run it in Win 7, I get tis error message:
    'This applications failed to start because it could not find or load The Qt platform plugin "window".'

    I used Dependency Walker trying to find out wht's going on.
    In the pictures, you see:
    on the left the folder which contains my program and the files, dlls.
    on the right the Dependency Walker run in Win XP.
    alt text

    Files: icudt51.dll, icuin51.dll, icuuc51.dll, Qt5Gui, Qt5Core, Qt5Widgets.

    From G:\Qt\Qt5.2.1\5.2.1\msvc2010\bin or from G:\Qt\Qt5.2.1\Tools\QtCreator\bin?

    I tried from both but none worked.

  • @Panoss
    Do you have qwindows.dll inside platforms dir?
    This may also help you

  • (this blog you posted me was the first I read, but didn't help)
    Yes I do.
    I have it in /platforms, but also in the same dir with the .exe.
    Just to be sure it's everywhere!! :)

    And this is Dependency Walker run in Win7:
    alt text

  • @Panoss
    Did you try setting RPATH?

  • What is RPATH?

  • @Panoss
    In the doc section When building the the app
    Adding QMAKE_LFLAGS += -Wl,-rpath,"'\$$ORIGIN'" at the end of my .pro file .

  • According to the blog, this is for Linux.

  • Lifetime Qt Champion

    It seems you did it well.
    try installing the 2010 runtime on win 7
    (yes i know u have 2 files in folder but just for test)

    Also, are you 100% sure that compiling in xp, targeting xp, also produce a .exe that likes win 7?

    Also since the folder works under xp, i guess its not a missing Qt plugin as such but be either VS runtime related or
    dependency of a plugin

  • I repeated the process (from MSVC2010 command line: windeployqt C:/..blah...blah...) and now runs fine!!!!
    It has some more files than before.
    I 'll start removing files one by one to see which one was the problem.

    How can I make sure it will run on Win 10 64bit? (I have no access to Win 10 64 bit pc)

    Edit: the cause of the error was the libEGL.dll. When I removed it, the error reappeared.
    When I put it back, all fine!!!

  • Lifetime Qt Champion

    How can I make sure it will run on Win 10 64bit?

    Only by running it on one.
    Just zip the folder and share on dropbox to one of your friends. He can test it very fast.

  • I 've done this, works ok, but I was thinking how can I be sure it will work ok in every Win 10 installation?
    Because it has happened to me before (with Python and Qt) worked on one installation of Win 10, didn't work on another installation of Win 10.

  • Lifetime Qt Champion

    You cannot.
    You can only test and hope.
    But if it works in one, then big chance it works in next too.

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