The error message that some other app might be using the camera mightblock your camera app from using the camera.
To find which app is using the camera :
- Run Settings > Privacy > Camera
- Scroll down to "Allow desktop apps to access your camera"
- Verify that the last entry in the list is from today.
When you know which other app has taken control of the camera, you mightbe able to block it (or use it as your camera app).