Just a heads up because this hurt.
Flying Berlin to London with a minor. The app said we had to go to the check in counter to print boarding passes because they couldn’t be issued digitally. I figured it was because I was traveling with a child.
Got there 3 hours early. At the counter they basically ignored the app message and charged us £55 per person to print them. There were three of us.
Same thing almost happened again on an Edinburgh to Germany flight. After digging through forums I found out the issue was the app version. Once I updated it, the digital boarding passes worked.
So yeah… if the app says it can’t issue your boarding pass, double check you’re on the latest version before going to the airport. Might save you a lot of money.