Maran the Mishna Berurah (Siman 493, 2) ruled that if a person happens upon something that requires the Shehecheyanu blessing, they should recite it. Rabbi Chaim Kanievsky of blessed memory explained that the Mishna Berurah did not mean only if it “happens” by chance, but rather that it is permitted initially to seek out something new in order to recite Shehecheyanu. One who examines the authorities will see that many stated there is no source or trace of a custom to avoid reciting Shehecheyanu during the Omer, as elaborated by the author of Levushei Mordechai (Siman 153), the Kaf HaChayim (Siman 493, 4), and Maran in Yabia Omer (Vol. 3, Siman 26). However, those who are stringent have upon whom to rely, as Rabbeinu Yerucham—one of the great early authorities (Rishonim)—explicitly wrote not to recite Shehecheyanu during these days because they are days of judgment. I found similarly in the book Leket Yosher, who was a student of the Terumat HaDeshen, in Ollelot Ephraim, and in the book Tzror HaMor. Therefore, one who has a custom not to recite Shehecheyanu would require the annulment of vows (Hatarat Nedarim) to be able to recite it during these days (Tosafot Chayim on the Chayei Adam). We add that according to the Ben Ish Chai, even for those who are stringent, it is certainly permitted on the Shabbats of the Omer, on Lag BaOmer, and on Rosh Chodesh.