Can not open in windowed mode in Qt 5.15.2

[swdmnd]

I followed the tutorial but can't open the app in windowed mode.
The error is:
qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in ""
Could not set DRM mode for screen HDMI1 (Permission denied)
Could not set queue DRM page flip on screen HDMI1 (Permission denied)

If I run a program from console mode, it runs in fullscreen.
What should I do? I want to be able to run qt programs in windowed mode.

[UmutDumandag]

I got the same error as well. Did you solve the problem? @swdmnd

[swdmnd]

I haven't found a solution for this. I think qt is trying to access the hardware directly instead of using X. I don't know where to start.

[cubit9-danielpeyer]

Did you try this? I had the same problem.

nano .profile
and add at the end of the file
export QT_QPA_EGLFS_ALWAYS_SET_MODE=1
save and close.

Logout and login again ... Start your Qt program

[fcyinxunpeng]

@swdmnd hello, did you fix this problem?
i set the env QT_QPA_EGLFS_ALWAYS_SET_MODE=1 in .profle
and when i switch to tty1, by press ctrl+alt+f1, it can show my app