I got message close to that a month ago when returning fron Visby. I could do the check-in, but not get the boarding passes, the error message was like yours, also saying that mobile boarding passes cannot be used at this airport.

Didn't think it was nothing to worry about, just wondered how it can be possible that there is an airport in Sweden that doesn't accept mobile boarding passes. Well, in any case thought better be at the airport a bit earlier, so arrived there one hour before departure and asked the lady at check-in to print out our boarding passes. She tried, number of times, but constantly got error messages that there are some unpaid fares As we had arrived with same tickets one day earlier, the same issue should have come up already at HEL if there were some issues like that. After 5mins she told she has to call Helsinki to clear this issue and left to the office. While waiting they already closed the check-in and some 20mins later she returned with our boarding passes - hand written on empty totally white boarding pass coupons: AY628, VBY-HEL, Purjelentaja/Mr, 1B, as she said there was no way she could print out real boarding passes, and not even IT support in Helsinki could find any way to do it. She was even kind enough to follow us to the security check and told the security officers that these boarding passes are really real, not mickeymouses. At the gate no problems, as it was same friendly lady taking care of boarding. So finally got on the flight, but not too much with excess time at the departure area. After this NF onboard tasted good

So based on my experience, after any such strange error message I would get early enough to the airport.