Comment 8 for bug 1427946

I suspect at shutdown, the "QScreen" backing the qquickwindow is deleted before the qquickwindow is closed - when that happens, qt still has gl resources it wants to release, so tries to acquire a new shared gl context and release them, before shutting down properly.

But this causes qtmir to try creating a new QPlatformOpenGLContext which tries to create a Display, while mir is shutting down, and I suspect the egl state is not suited to that.

Proper solution is to implement a QPlatformOffscreenSurface and use it on shutdown