We do not recommend updating the iPhone 4S, iPod Touch (5th generation), iPad 2, iPad (3rd Generation), or iPad Mini (1st generation) to iOS 8
We are seeing reports that the upgrade from iOS 7 to 8 is deleting random apps from devices. Be sure that all of your photos are uploaded or that you save all of your photos using iTunes before upgrading. See this article for instructions on saving photos with iTunes: https://pruvan.zendesk.com/entries/25802993
Make sure that the first time you open the camera in Pruvan, that you select 'yes' when asked if you want Pruvan to have access to your camera.
If you are having an issue with your app closing when you try to enter the camera do this: