Is one allowed to be matir a neder on Chol HaMoed that is not le’tzorech ha’moed at all?
Answer:
There is no melachah involved in being matir a neder, and therefore there would not appear to be any problem in undoing a neder on chol ha-mo’ed, even where doing so involves no need for the mo’ed itself.
This ruling is given by the Raavyah (838, based on Mo’ed Katan 12b), and by other poskim (see Mordechai 856; see Darchei Moshe 531:1).
Although there is some tircha involved in being matir a neder, and for this reason it is forbidden to perform the hatarah on Shabbos where there is no need for it (see Mishnah Berurah 341:1), the tircha is presumably considered very slight, and therefore not sufficient to prohibit on chol ha-mo’ed.
