If your computer displays an error message stating: It appears another app is using the camera,” then there are a number of potential solutions for troubleshooting this problem.
One way to solve this issue is to close down any suspicious apps that access your camera, like those listed above. To do this, right-click an icon in your system tray and select Exit, Quit or Close from its menu. Alternatively, you could check its recent activity by going into Settings, Privacy & security and scrolling down until reaching Camera option.
Launching programs such as GPU-Z or HW Monitor to monitor CPU, memory and disk usage can help identify processes consuming excessive resources; then terminate them to free up resources. Finally, scan your system with Malwarebytes Free for malware.
Once connected to your computer, try switching the USB ports that your device is plugged into to see if that helps solve camera-related issues – this may also be beneficial when connecting external devices such as hubs. Also install any available updates for both camera and computer such as firmware/driver updates available through their respective websites as these could often resolve 0xA00F4243 errors. Also ensure your antivirus software remains updated so your computer remains safe against potential malware attacks.