Cannot background app on iOS

qioscontext.mm:327:auto (anonymous class)::operator()(Qt::ApplicationState, Qt::ApplicationState) const(): explicitly glFinishing and deactivating QOpenGLContext(0x280269970, nativeHandle=QVariant(Invalid), format=QSurfaceFormat(version 3.0, options QFlags<QSurfaceFormat::FormatOption>(), depthBufferSize -1, redBufferSize -1, greenBufferSize -1, blueBufferSize -1, alphaBufferSize -1, stencilBufferSize -1, samples -1, swapBehavior QSurfaceFormat::DoubleBuffer, swapInterval 1, colorSpace QSurfaceFormat::DefaultColorSpace, profile  QSurfaceFormat::NoProfile), surface=0x28246d630, screen="iPhone built-in display")
qioscontext.mm:337:None(): ASSERT failure in QIOSContext: "OpenGL ES calls are not allowed while an application is backgrounded", file qioscontext.mm, line 337