We are planning on taking the RER B from CDG on 26 April to Gare du Nord. And, again when we return to CDG on 20 May from Denfert-Rochereau. I’ve been trying to understand the “no service” warnings on the https://me-deplacer.iledefrance-mobi...e-reseau-ferre. Can anyone please help me understand if the service work on the RER B will prevent us taking these two routes on our dates? Thank you. PDF notice attached.

If I read the dates correctly, you should have no problems. In April the work ceases on the 18th and in May it begins on the 26th.

I have the same question
arriving on Sunday Monday (March 6)

was planning to take the RER B to Les Halles
noticed that alternate (and longer) routes are being offered

any advice?
should we take a taxi or Uber?
I have never used the bus
2 adults with light luggage

You can either B5 or B4 bus to Stade de France Saint-Denis and take the RER D to Chatelet-Les Halles.

The Roissybus (Opéra), bus 350 (Paris Porte de la Chapelle), and bus 351 (Nation) will take you directly into Paris.

There are always plenty of taxis at CDG. What might cause a wait or backup is the very inefficient way in which passengers are boarded.

The RER B service does continue but portions of the route will be operated by replacement buses.

Thank you for the information. Seems like we'll have a few options.