At the top of https://www.sncf-connect.com/en-en/train-ticket
it says this today in English:
National interprofessional strike on March 13 and 14
Due to a national interprofessional strike, the traffic of trains is disrupted on Monday 13. We invite you to postpone your journey free of charge to another date, or to cancel your journey and obtain a full refund.
The French version on http://www.sncf-connect.com/
has this to say today:
Mouvement social national interprofessionnel ce lundi 13 et 14 mars.
La circulation des trains est perturbée sur le réseau SNCF le lundi 13 mars 2023.
Le trafic devrait rester perturbé sur la journée du mardi 14 mars.
Nous vous invitons à vérifier la circulation de vos trains et correspondances sur vos canaux d’information habituels la veille à partir de 17h00.
But as a forum member discovered only two days ago, some trains run from Paris to Bayonne and some trains run from Bayonne to SJPP despite the strike. In fact, because other passengers had cancelled their tickets, she could book herself on a high speed train that had previously been fully booked and she arrived fast and without problems in SJPP. Despite the strike.
Which is why it makes sense to check one’s own dates and journey. People who have booked a ticket and communicated their email are notified anyway when their train has been cancelled for the following day.