This issue can be software or hardware related. Before contacting your device manufacturer, you can try several possible solutions to this error:
- Restart your phone - turn off your phone, wait for about 10 seconds, and then turn it on again. This can fix some minor software related issues.
- Remove any third party camera apps - Uninstall any third party camera applications that you have downloaded to your device. The phone might have received an update for its software, and we might not have had the chance to update our app yet.
- Uninstall other apps - There might be a bad app that's the culprit of this issue. Think of the latest apps you have downloaded/updated around the time that this issue started to occur and uninstall them. After uninstalling, open your camera and see if the phone is still displaying a black screen.
Note: According to reports from other users, Cyanogen and in other ways modified OS's are not implementing the Camera functions properly and Photomath won't work.