Hi,I just got a new Nokia 8 through the post today and the back camera does not seem to be working at all. After I completed the initial set-up I opened the camera app which crashed immediately. I've also downloaded a third party camera app (open camera) which works with the forward facing camera, but gives the error message 'failed to open camera, may be in use by another application?'
I'm not an expert, but the actions below worked for me when I got a 'cannot connect to he camera' error whilst messing about with different camera apps. This is assuming that you have not got a hardware problem with your particular phone, which would require sending it back.
I went into Settings/Apps & Notifications and selected the (stock) camera app. I then selected 'Storage' then selected 'Clear Cache' then 'Clear Data'. The Clear Data button will warn you that the app will lose camera data and settings. I then returned to the previous menu for the camera app and selected 'Force Stop' then 'Disable'. Again it warns you do you really want to do this or something similar.
I then selected enable (the camera app) and came out of the settings menu. you will find that the camera app shortcut will have disappeared from the dock at the bottom of the home-screen, but it is still in the app drawer, so you only need to drag and drop it back in the dock to get it back.
When you open the camera app again, it will cycle through the various permissions, location, storage, microphone etc, just allow them all. Hopefully, if it was just a software glitch the camera should open OK for you.