Q. Can you say kidush levanah on the eve of asarah beteveth, since it is not a happy time, which is required for kidush levanah?

A. Indeed Nitey Gavriel (Chanuka 64: 1) mentions that Belz and others refrain from reciting kidush Levana on the eve of Asara Beteveth. This being similar to the three weeks period and its restrictions, which begins from the eve of Shiva Asar Betamuz and not from the morning when the fast starts.

However, in locations where at this time of the year cloudy days prevail, Horav Shlomo Miller Shlit”a recommends to recite it.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a