The great wonder

The Mechaber in Shulchan Aruch (O. Ch. 580) lists additional fast days.

One of the fast days is on the 9^th day in Teves. “It is unknown what

Tzoroh happened on that day”.

The Taz  writes" תימה גדולה  (It's a great wonder) that the Bais Yosef

doesn't know what happened that day,In our Selichos (Ezkero Motzok)

it is written that Ezra Hasofer died on the 9^th of the month".

It is interesting, this Piyut is said, only by Ashkenazim. The Sefardim

say instead the Piyut “Sha’a Elyon” and the Piyut “Yoshev Bashomayim”.

In both of these Piyutim, it is mentioned that Ezra Hasofer died on the

10^th of Teves.

The Mechaber, being a Sefardi, must have held that Ezra died

on the 10^th and therefore didn’t know what happened on the

9^th of Teves.