The best is to book at a ticket office in Croatia once you arrive there. Price is around 1€.

I did once see this train bookable on the Eurail website but:

• The reservation was on paper only and would be sent by post.
• The costs were 3€ + 2€ booking fee + 9€ postage fee, which is outrageous IMO for something that costs 1€ locally.

Are the trains likely to be full or is it just an issue with online booking

ALT; he bus runs ev 30 mins in much shorter time too-busstation is a short tramride away.

It indeed seems that this is the new ESpana for passholders-as its about the only railline going to seaside and has very few-and very short trains left=tailored to demand in off-peak times. There are also in summer several non-daily special holidaymaker expreses coming from much further on-these will not take passes and are likely to be full anyway already

AFAIK the only one that does not take passes is RegioJet.

You should be OK to book a few days in advance locally. It's just an issue with online booking.

I’m having similar issues for online booking, and I’m going to travel in a few days in eastern Europe (Budapest-Bucarest-Istanbul). 

Since online booking via app is currently unavailable, or tickets are sent through postal shipment and it requires too long, I was wandering: will I (reasonably) be able to buy reservations for night trains locally?

And if so, are discounts for passholders applied?

Thanks in advance for any response!

No, it’s f**** not the best option to book in Croatia!

How can you risk full train? If you don’t have any option to buy it in advance.

Don’t listen to this guy cause it’s extremly stupid and it prooves that interrail is a fraud!

Actually, no, not really.

Yes, booking in advance is always the best option generally speaking, but there are many factors that must be considered. The first and most important is that not all train companies have a built-in system for discounted tickets for Interrail passholders. Sometimes buying a few days in advance is worth the risk, especially in eastern Europe (not sure about Croatia though).

This proves that Interrail APP is a scam: Interrail in general is great. If you travel a lot, even with night trains, you will save A TON of money. But the cluncky app, the non-integrated system of booking, and the reservation fees make it a scam, I agree.

At least one of the night trains Budapest - Bucharest can be booked via ÖBB and you'll have an electronic reservation. For the others, booking at a ticket office or by phone should be possible, e.g. via ÖBB (+43 5 1717) and then pick up the reservation if you pass through Austria. Also check with Trenitalia (assuming you're still in Italy).

Bucharest - Istanbul can only be booked at a Romanian ticket office or directly from the coach attendant. It is not likely to be fully booked.

It would appear when you try to book a reservation on Croatian trains that there is a possibility of getting a paper copy, with it sent by post.  But it isn’t!  If you follow through the reservation system, at the last hurdle it throws you out saying it’s not possible.  I even arranged with a hotel owner in Croatia to use their address to get the ticket sent there in case getting it sent abroad was an issue, but that didn’t help. It would be better if it said right at the beginning that it was impossible.  I must have tried about 20 times, with the same result.  I did get the reservation once I was at a ticket office in Croatia, but beforehand it’s not possible.