Paper t+ tickets (Paris Metro, bus, tram, RER central zone) are being slowly withdrawn, no new stock is being issued so these trains that were selling them are or have already run out of them.

Unless they switch to selling one of the Navigo smartcard varieties the useful facility to buy on board and avoid a scrum at various Paris terminus stations will be at an end.

Oh no!!  Thanks for the update Al.

That is such a nuisance - and just before the Olympics too.

Handily, the Mayor is doubling the price of Metro tickets for the Olympics. And she’s already tripled the nightly tourist tax on your hotel room! (One 4* hotel room, at full occupancy, now earns €6,000 a year in tax.)

It looks like it is possible to buy t+ tickets in the Île-de-France Mobilités app:

https://www.iledefrance-mobilites.fr/en/tickets-fares/detail/ticket-t-on-navigo-easy-travel-card-or-on-your-phone

As Ralderton mentions, the prices will double during the olympics - I think it is from the 20th July. I am traveling trough Paris on the 23th July, so it it my plan to buy a t+ ticket a few days before the 20th July.

I haven’t tried it yet, but I hope it works… If not, it is only a €1,85 price difference. But my main reason for buying the metro ticket in advance, is that I don’t want to stand in line to buy it at a very busy metro station.