FaceTime Camera: "Your camera is in use by another application" message
The FaceTime camera can be used by one application at a time. The message, "Your camera is in use by another application" may appear when you try to video call.
If you receive the above message, follow these steps:
Quit all applications that are using the FaceTime camera. If you don't know which applications might be using the FaceTime camera, quit all open applications. Examples of some (but not all) applications which can use the FaceTime camera include iChat, iMessage and PhotoBooth.
Open only one application and use the FaceTime camera.
If the issue persists and you are using an external camera, unplug the connecting cable from your computer and the camera, wait a few seconds, and then firmly (without forcing) plug the cable back in to the camera and the computer.
FaceTime is not available in all countries or regions.
Information about products not manufactured by Apple, or independent websites not controlled or tested by Apple, is provided without recommendation or endorsement. Apple assumes no responsibility with regard to the selection, performance, or use of third-party websites or products. Apple makes no representations regarding third-party website accuracy or reliability. Risks are inherent in the use of the Internet. Contact the vendor for additional information. Other company and product names may be trademarks of their respective owners.