No Qt platform plugin could be initialized

Tom_B

After reinstalling from win 10 to win 11 I would like to upgrade current qt installation.

When running on-line qt installer

qt-online-installer-windows-x64-4.9.0.exe

the following error occurs:

This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem. Available platform plugins are: direct2d, minimal, offscreen, windows

I read a lot of articles regarding this issue. I tried to copy the content of the folder

qt6\plugins\platforms

to the installation folder, but nothing happend.

Suprisingly, other SW like QtDesigner from the previous installation as well as LyX work.

The older installer

qt-unified-windows-x64-4.6.1-online.exe

works well but all newer installers since

qt-unified-windows-x64-4.7.0-online.exe

...
generate the above-mentioned error.

Thanks for your help...

jsulm

@Tom_B said in No Qt platform plugin could be initialized:

ould like to upgrade current qt installation

If you already have a Qt installation then you can simply use the Qt maintenance tool to install/remove Qt versions and tools.

Tom_B

Unfortunately, neither current installer nor the Qt maintanance work. Only old versions of both, as I wrote. I have been using Qt more than 10 years, but this never happened to me.

Tom_B

I deleted the Qt folder content. Now, I am able to run

qt-unified-windows-x64-4.6.1-online.exe

and install Qt. However, trying to use Qt maintenance tool, the above mentioned error occurs.

hskoglund

You coild try installing Qt as another user on your desktop (via Settings, Accounts, Other Users, click "Add account")

Tom_B

Installation as a new user as well as Qt maintanance SW work well. After the user is switched to the old one, the same error occurs.

Tom_B

The same issue on my notebok with Win11. After unistalling old version of Qt, the new installator throws the same error. Probably some remaining hidden settings, lost items in registry or environments settings?

jeremy_k

Setting the environment variable QT_DEBUG_PLUGINS to a non-zero value should result in information about the platform plugin loading to be dumped to the console. Sometimes it provides very direct and actionable feedback, eg reporting a missing dependency or version mismatch.

Using QT_WIN_DEBUG_CONSOLE is probably also necessary.

Further documentation: https://doc.qt.io/qt-6/debug.html#environment-variables-recognized-by-qt

Tom_B

Thank you very much for your comment. I set both varibles to 1 in both sections, User variables and System variables, restated the PC. However, the qt installator threw the same error code and did not start.

Tom_B

I found the solution. Deleting the User/System variable

QT_QPA_PLATFORM_PLUGIN_PATH
c:\Users\Tomas\AppData\Roaming\Python\Python36\site-packages\PyQt6\Qt6\plugins\platforms

solved the problem. Probably this value is a residual from a previous installation that was not removed. The new installator is sensitive to this item.

jeremy_k

@Tom_B said in No Qt platform plugin could be initialized:

Thank you very much for your comment. I set both varibles to 1 in both sections, User variables and System variables, restated the PC. However, the qt installator threw the same error code and did not start.

QT_WIN_DEBUG_CONSOLE expects a value of new or attach. 1 is probably the same as not setting it.