You can buy a reservation for ÖBB Nightjets and Euronights that are Nightjet Partners on tickets.oebb.at → discount: Interrail/Eurrail

Which night train exactly on which date?

ÖBB night trains can be booked on the ÖBB website and you'll normally get a PDF ticket.

This is not true. I went to the ÖBB website and their App and you can book the regular trains but not the night trains. Their tickets are listed as unavailable even a month in advance.
 

Furthermore I’ve spent A lot of time on hold on their service number and I burn to about $10 of skype credit while waiting on hold - which is a raoed about nine times what it is to call other European numbers. 

i checked a number of days and same thing 

I've booked Interrail/Eurail reservations on the ÖBB website multiple times.

Please let us know which train on which date you would like to book, so people can help you.

Thanks for sharing the train details. The night train Zürich - Praha (it is actually just 1 through coach) is managed by Czech railways and you can book it via their website.

Don't forget to add your Eurail pass. Click on "Buy” and then on “Continue” and then you can change the compartment type if you want (and change male to female if needed). The fare shown is the cheapest reservation available, for a shared 3-bed compartment.

I'm not sure why ÖBB don't sell this reservation online :/

When I attempt to buy through Eurail it only offers a paper ticket to be mailed. That’s a problem when you are traveling. 
 

I did call Czech number and it was great - someone answered and they had an English speaker. Only problem is no discount for Eurail passes on night train. The price is $186 for two which is higher that $140 Eurail charges. 
 

ÖBB never answered even when calling at 6 am or 8:45 pm. You can stay on hold indefinitely. Their number won’t work on google voice and costs about $10.80 an hour on Skype while you hold. Eurail should change their recommendations to call them - and/or make the reservation system provide etickets. 

It's not so great that they tell you incorrect things. Eurail IS valid and the price starts from the price shown in the screenshot above, which is the sleeper supplement you will have to pay.

Shared 3-bed compartment: 1184 CZK = ~54 USD p.p.

Shared 2-bed compartment: 1525 CZK = ~69 USD p.p. (which corresponds with your Eurail price).

If you order yourself via cd.cz, as I suggested earlier, you receive the reservation as PDF via email.

Edit: the price of 186 USD corresponds with a 2-bed Deluxe compartment (with shower and toilet) for 2 persons (2051 CZK p.p. on cd.cz)

Please note, that you need to print your reservation for CD Nighttrains. (i hope I’m up to date, last time I needed to print it). 

I spoke to a Czech operator at the train company a few hours ago and she told me

1  yes they can send an eticket 

2 but that the Rail Pass is only good for the non-sleeper trains and there’s no discount for the EuRail Pass.
3 She also told me as you did that I can buy it directly from the Check site however both yesterday and today that’s not possible. It’s possible to buy other tickets which are not night trains.

so this seems impossible 

Here’s what the bottom of it looks like for most trains on the Cd.Cz site …. And then what the sleeper train looks like - despite operator saying it’s available 

I finally resolved this - after trying to reserve via Eurail, OBB, CD.CZ, and SBB websites, and calling OBB, CD, and SBB.

The solution is to call SBB, and wait a few seconds until you hear English (after they cycle through German, French, and Italian). You can’t book the train but you can reserve it, and then pick up the paper tickets in their train office before the train leaves. 

What a shame they're so uninformed. The Eurail pass is also valid in night trains of the participating operators and you just have to pay the reservation supplement.

I just tried the Czech site for a sleeper reservation Zürich - Praha and could get to the payment page. I didn't test payment though.

To memorialize my experience Nov 2021 trying to get a night train from Zurich to Prague. Train is actually Czech, but they affiliate with Austrian Night jet system, and Swiss rail. Non-night train tickets work much easier. 

Calling :

OBB (Austria) - a complete waste of time, and will cost tens of dollars just listening to an endless loop of German

CD.CZ (Czech) - Great phone service - in English. However they don’t recognize Eurail pass. $186

SBB (Swiss) - Good phone service - in English. At first they gave me full fare, then only when pressed did they find that Eurail price. This turned out to be the solution. 

Online :

Eurail - works but requires a paper ticket mailed to. you while you are traveling - fatal flaw $140 for 2

OBB - Ticket not available for night train

CD - Ticket not available for night train - but would have been e-ticket if it worked

SBB - Ticket available at $320