Cannot switch to second camera for scanning QR code

[oliver]

• Operating System (Linux/Mac/Windows/iOS/Android): Linux Mint 22.2
• Delta Chat Version: v2.53.1 (installed via Flatpak)
• Expected behavior:
  • I have installed DC on a laptop, and after installation I selected "Add as second device" and saw the camera image for scanning the QR code. This was the image from built-in camera, but I wanted to use the image from an external USB camera (which I can move around more easily). The gear menu shows the second camera (nice!), but when selecting this entry there is a short spinner on grey screen, and then the built-in camera is used again. I have already restarted DC (exited it via tray icon), but that did not help.
  • btw. after plugging in the external camera I had to re-open the whole dialog to make the camera appear in gear menu. Not a big problem, but maybe difficult to discover.
• Actual behavior: see above.
• Steps to reproduce the problem:
  • use a laptop with a built-in camera.
  • attach a USB camera to the laptop.
  • install DC via Flatpak.
  • start DC and pick "Ich habe bereits ein Profil" (I have a profile).
  • pick "Als Zweitgerät hinzufügen".
  • open gear menu in lower right corner.
    • there should be two cameras listed, and the first one should have a checkmark.
  • pick the second camera.
  • desired behavior: video images from second camera are shown.
  • current behavior: video images from first camera are shown.
• Screenshots:
• Logs:

[oliver]

Log file: 2026-07-11-12-38-17.log

[WofWca]

This is the code:

deltachat-desktop/packages/frontend/src/components/QrReader/index.tsx

Lines 327 to 407 in bff8ca8

	const startStream = async () => {
	const videoConstraints: MediaTrackConstraints = {
	deviceId,
	facingMode: 'user',
	}
	try {
	setReady(false)
	// Stop all streams if some existed before we begin a new one
	stopStream(activeStream)
	try {
	const permission_status = await runtime.checkMediaAccess('camera')
	if (permission_status === 'not-determined') {
	if (!(await runtime.askForMediaAccess('camera'))) {
	log.error(
	'runtime reported that permission request was denied by user'
	)
	setCameraAccessError(true)
	return
	}
	} else if (
	permission_status !== 'granted' &&
	permission_status !== 'unknown'
	) {
	log.error('runtime reported that permission is not granted:', {
	permission_status,
	})
	setCameraAccessError(true)
	return
	}
	} catch (err: any) {
	if (err.message !== 'UnsupportedPlatform') {
	log.warn('failed to check for runtime media permission:', err)
	}
	}
	const stream = await navigator.mediaDevices.getUserMedia({
	video: videoConstraints,
	audio: false,
	})
	if (unmounted) {
	stopStream(stream)
	return
	}
	const videoTracks = stream.getVideoTracks()
	if (videoTracks.length === 0) {
	stopStream(stream)
	throw new Error('no video tracks given')
	}
	video.srcObject = stream
	activeStream = stream
	const settings = videoTracks[0].getSettings()
	let isFacingUser = true
	if (settings.facingMode !== undefined) {
	isFacingUser = settings.facingMode !== 'environment'
	} else {
	isFacingUser = !videoTracks[0].label.toLowerCase().includes('back')
	}
	setFlipped(isFacingUser)
	if (settings.deviceId) {
	setDeviceId(settings.deviceId)
	}
	if (settings.width && settings.height) {
	canvasRef.current.width = settings.width
	canvasRef.current.height = settings.height
	}
	setReady(true)
	} catch {
	stopStream(activeStream)
	setCameraAccessError(true)
	}
	}

This has also been mentioned here: #6373 (comment)