What times and what trains are you booked for?

Marseille is rather out of the way for a Barcelona - Paris journey.

We are spending a couple of days there before the train to Paris . Put it down to bad planning at the end of our trip haha

So you aren’t trying to connect to a Marseille - Paris train on the same day then, that makes more sense.

Times for Barcelona - Portbou - Cerbere are here

https://rodalies.gencat.cat/web/.content/02_Horaris/horaris/R11.pdf

From Cerbere you will be taking the unreservable RER to Narbonne and changing there.

The faster reservation compulsory Narbonne - Marseille Intercities are mostly full for tomorrow but there are some RER connections.

One example

Barcelona Sants 0916 - Cerbere 12.04

Cerbere 12.26 - Narbonne 13.55

Narbonne 14.34 - Marseille 17.47

No reservations required or possible for any of these.

Thanks for that. It’s pretty much what we thought which is fine. We did not plan to end up in Barcelona hence the difficulty! The confusion centres more around the Eurail app showing the train change in Cerbere as involving public transport between trains . I’m assuming we arrive and depart from same station?

It shouldn’t say that.

It is one station, it won’t take long to change there.

Thanks .. I was fine with the long journey.. my fault haha but was thrown by what it said! 2 months travelling and it’s been great didn’t want to fail in the last days haha

I suspect the reason for the “tranfer by public transport” is that Interrail planner has Cerbere as 2 stations listed, Cerbere (France) and Cerbere (Spain) and somebody has programmed it as needing a physical transfer. This happens in many border stations so it doesn’t inadvertently trip Country of residence or single country pass issues. Somebody from the South of France could use local trains to get to Cerbere France and then activate their IR pass onward to Spain from Cerbere Spain, saving the COR day for any subsequent travel in France,