Many iPhone users while trying to make video calls using FaceTime are facing issue with starting the call. FaceTime app popsup with the error message that the camera is busy and can not be used. Your iPhone camera can be used by on app at a time and if the is used by other application at a time, the Facetime pops up with The message, "Your camera is in use by another application" may appear when you try to video call.
To solve the Facetime camera busy Pop up issue, please check and confirm below:
Solution 1: Camera used by external apps
You may be using an external camera, unplug the connecting cable from your computer and the camera, wait for some times, and then firmly plug the cable back in to the camera and the computer.
Solution 2: Safari Browser camera access
More likely it is when you might have used your Web Browser on a site that can use your camera, this can access to your camera and Mic via a Flash Plug-in. Close safari in this case and try again.
Solution 3: stop Installed apps using camera
Settings > Privacy > Camera will show 3rd party apps that have requested and/or are authorized to us the camera. Remove all from list if you don’t use them.