You can claim from Interrail here. Include any receipts and explanations of alternative arrangements you had to make.

I may be wrong, but I think anything beyond the basic delay compensation has to get sent to SNCF, who will probably ignore or refuse.

I don’t know if the strike makes any difference to their obligations to get you to Barcelona. It may depend on when the strike was announced (whether or not you personally knew about it.)

https://www.interrail.eu/en/support/delay-compensation

SNCF is notoriously late in these things. You haven’t heard anything yet of SNCF?

You can always file a complaint with the SNCF mediator if you deem SNCF’s response unclear: https://mediation.sncf-voyageurs.com/?lang=en

Delay compensation is also possible at interrail (but isn’t that much) https://www.interrail.eu/en/support/delay-compensation

Operators are required to offer an alternative option at no extra costs if you still want to travel. If they refuse (or haven't offered anything within 100 minutes after you stranded), then you're entitled to be reimbursed reasonable extra costs you had.

As to where to claim: on top of compensation for delay, you can claim through Interrail "unavoidable costs incurred in order to reach the original destination”.

Thanks for the replies which all have valuable information for me.

I got soon after the travel in contact with Interrail via the delay compensation form. We got imbursement for the delays, but my request for the extra costs was ignored. In a second attempt they told me to get in contact with SNCF. So I did, but my two attempts we ignored. That is some months ago, so I don’t expect a response any more. The SNCF mediation page is new for me. May be that is the way to go. Also at my case with Deutsche Bahn, I only had success when using the mediation in Germany.

@rvdborgt: we had seat reservations from Valence TGV to Barcelona. When we got on the train in Valence, the SNCF personal told us that we will get help at the station of Perpignon. Arriving at Perpignan, there were really not a single SNCF person to ask because they all were on strike. Even the beverage vending machines and the toilets were out of order. Therefore, no alternative option was given to us.

I just tried to fill in the form of the SNCF mediator. After explaing in detail my case, I had to give my contact data including a phone number. Whatever I filled in on that field of the phone number, it was not accepted. It said: “Your entry does not match the allowed pattern.“  Unfortunately, they do not explain what is the allowed pattern. Is there something special with phone number formatting in France which I do not know?

Try 0049 or +49 before the rest of your number.

I tried everything what me occurred including 0049 or only 49 or +49 or ++49. I tried with blanks and without blanks, … Nothing worked.

If all else fails, just make up a number in the French format. A 10 digit number starting with 07

Or 06. And then mention your real phone number in the message.