There are three reasons why this message comes up.
- You did not give the Screen Mirror app permission to use the camera; OR
- Your iPhone screen is off
- The USB connectivity is not working well
Give camera permission to the Screen Mirror App
On the Mac, go to
System Preferences | Privacy & Security | Camera
Make sure that Screen Mirror app is checked.
iPhone/iPad screen is off
There are some users who have reported this. I have seen it occur more often when the phone is an iPhone 11 or higher. There are two solutions.
- Unplug and Plug in the iPhone/iPad over USB. Sometimes this will resolve the problem.
- Reboot the iPhone, this usually solves the issue
It is not often that this happens, This is a solution if you run into the issue. This is not an issue with the Screen Mirror app but with the iPhone software. Other applications report this issue too.
Apple has the same suggestions.