Question:
Was there tisha bav during the bayis sheni?
Answer:
Huge machlokos.
Sources:
Mishnah Rosh Hashono18a יוצאים (אף) על אייר depends if we leave the word “אף”, Tosefos Rosh Hashono 18b ד”ה הואיל , Rambam Perush Hamishnayis. Gevuras Ari ibid, Magen Avrohom 51:11, Teshuvas Chasam Sofer O:CH 157. and much more.