A black screen is usually caused by camera permissions, another app using the camera, or a locked device.
Answer
If the connection is established but there's no video, camera permissions or device state are usually the cause.
What to try
1. Check that camera access is granted to the browser 2. Make sure no other app is using the camera (e.g. a call app) 3. Confirm the camera device screen is not locked 4. Reload the page to re-acquire the camera 5. Try a different browser
Notes
On iOS, only one app can use the camera at a time
Check camera permissions in your device's `Settings > Privacy`