Hi @Alpina19, let me see if I can help out here!
Have you tried clearing data for the camera app? This will reset all settings for the app which might do the trick. To do this on your M5, find and tap Settings > Apps & notifications > See all XX apps > Camera > Storage > Clear data > Restart the phone.
Another thing that you can try is to reboot your phone in safe mode to see if you receive the same error message there. All apps downloaded from Play Store is temporarily deactivated while in safe mode and by doing this, you can see if this error message is caused by a downloaded app. For more information on safe mode and how to use it, click here.
If the same error message appears in safe mode, I recommend that you try to repair the software on the phone using a computer and Xperia Companion. Keep in mind though that a software repair will erase all user data from the phone, so remember to do a backup of your user data before proceeding with the repair.
Try these measures and let me know how it goes!
