Unfortunately quite a few different groups are planning to either strike or protest on Wednesday March 9. (Strikes officially began at 8 pm the evening prior, that is Tuesday March 8, and finish at 8 am the morning after, that is, Thursday March 10).
All four unions of the French rail company SNCF are striking, creating difficulties for rail passengers across the country.
several unions of the Paris transport authority RATP are striking, creating difficulties for local transport in and around Paris.
In addition, several young people's groups will be protesting, marching hither and thither, likely creating even more transport problems (I.e. certain streets will be blocked too, meaning that a taxi/Über probably is not going to be a magic solution).
Consult SNCF's and RATP's traffic information sites, as well as Twitter feeds of both of those and individual metro and RER lines and the Paris Police Prefecture and the Aeroports de Paris for information (both of the latter are good about putting ALL their tweets in both English and French).
http://www.sncf.com/fr/horaires-info-trafic
http://www.sncf.com/en/passengers
http://www.ratp.fr/informer/trafic/trafic.php
Sorry not to have better news. Good luck to those of you visiting or traveling on Wednesday.