Check that another app isn't using your device's camera. If one is, close that app to remove the black screen on FaceTime. Make sure the camera lens isn't blocked.

Some other application using the camera might not have been closed and could be running in the background. Fix Camera being used by another application in Windows 11/10 ...

Camera reserved or blocked by another app? Fix It looks as though another app is already using the camera, Error 0xC00D3704 on Windows 11/10.

Camera light being used by Camera. Either of these errors means that Flashlight or Camera app cannot be used because another app is using any or both of them.

However, phone camera app is also vulnerable to glitches and when inflicted, it starts to act up and become unoperational.

Camera issues on your Galaxy device can be a hassle to diagnose, but there are steps to resolve the most common software issues to get you back to shooting.