This may not be related to your particular issue. But, I ended up with a camera error after replacing the from and back casing on my S8. It took me a week before I realized I had missed this. You know how there are like up to 6 different cable connections on the galaxy phones? My S8 has that many that, every time I take it apart, I have to remember to plug them all in again. After I thought I had them all replugged, I turned my phone on and I couldn't get the camera to work. I looked to make sure everything was reconnected and Googled for some answer but couldn't come up with anything. It wasn't until I suddenly notice that there was a place on the motherboard where it looked like something should be plugged in. I took the phone apart again until I could more closely examine that area and suddenly realized I forgot to plug the front facing camera back in. So, I plugged it back in, reassembled the phone, and now the camera app works again.