This application failed to start because no Qt platform ...

tomy

Hi all,

I have this issue with running the Qt program Test.exe:

And I guess it's related to my Environment Variables Path, but there isn't any path of Qt there:

I'm using Qt Creator 4.8.1 (enterprise) on Window 10 x64.

How to solve this issue, please?

JKSH

You must put qwindows.dll inside a subfolder: platforms\qwindows.dll

Better yet, use the windeployqt tool: https://doc.qt.io/qt-5/windows-deployment.html

@tomy said in This application failed to start because no Qt platform ...:

And I guess it's related to my Environment Variables Path, but there isn't any path of Qt there:

That is not a problem. In fact, Qt should not be in your PATH.

SGaist

Hi,

Since you are starting your application from the explorer and from the look of the content of the folder, that's because you didn't deploy your application properly. You are missing the plugins directory.

Use windeployqt to deploy your application.

tomy

@JKSH , @SGaist
Hi,

You must put qwindows.dll inside a subfolder: platforms\qwindows.dll

I did this, and now no error messages. And nothing is shown when executing the file!

As for windeployqt, for the time being I like not to use it and run the program without it.

And what's the recommended directory to copy the .dll files from and paste them inside the executable folder, please?

mrjj

@tomy said in This application failed to start because no Qt platform ...:

As for windeployqt, for the time being I like not to use it

But its for gathering the needed DLLS ?
its nothing more than a copy helper.
So why on earth not use it?

Anyway, i like this site for info what minimum structure of the folder
http://www.tripleboot.org/?p=138

You would copy from the compilers folder under Qt.
"C:\Qt\5.12.0\mingw73_64\bin"

tomy

@mrjj
Hi mrjj,
Thanks. Your post solved the issue. :)

mrjj

@tomy
Super.
One note.
There is 2 version in the folder.
Like qt5Core
and
qt5CoreD
the D is the debug version.
Make sure to always compile in release mode ( your app)
and only copy the non D version to your folder.

tomy

@mrjj
Yeah, I knew these, but still thanks. :)

crush

This post is deleted!

crush

@JKSH hi,i did what you said,but still have the same problem.Can you tell me how to solve it,please?

mrjj

@crush
hi
did you use the windeployqt tool ?

crush

@mrjj not yet because i don't know how to use it

SGaist

@crush It's explained in the documentation.

Chris King

I am running into this message attempting to run Houdini. If I google this error message I find talk of many people running into this issue when running various apps. Autodesk Maya, Google One drive to name a few. Are all these vendors not properly installing their apps? Are users expected to modify their installations of these apps using windeployqt?

mrjj

@Chris-King
Hi
Make sure you are using a fully patch supported windows version. Win 7 might give issues.
It might not always be the vendors fault but some other installed app that added its folder to the global search path.
No, windeployqt is meant for the developers, not end user as for it to function, you need a Qt installation to get the
DLLs from. Besides the end user would have to know which compiler and Qt version that was used.

JKSH

@Chris-King said in This application failed to start because no Qt platform ...:

I am running into this message attempting to run Houdini.

Please provide the full, exact message. There are subtly different versions of the message; some include additional details which can help pinpoint the exact issue.

Are all these vendors not properly installing their apps?

Most vendors probably installed their apps correctly.

However, it only takes 1 badly-behaved app to cause DLL Hell and ruin things for everyone else on that PC. You'll need to track down that badly-behaved app and do something about it.

Are users expected to modify their installations of these apps using windeployqt?

No, users are not expected to do anything. Software developers are expected to provide well-behaved installers.