Divrey Hayamim Bais 30:3

3 For they could not keep it at its time, because the Kohanim had not set themselves apart as kodesh in sufficient numbers, neither had HaAm gathered themselves together to Yerushalayim.

Divrey Hayamim Bais 30:3 Meaning and Commentary

2 Chronicles 30:3

For they could not keep it at the time
In the month Nisan, as the Targum adds, on the fourteenth day of the month, as the law enjoined, because the cleansing of the temple was not finished until the sixteenth day, see ( 2 Chronicles 29:17 ) and, besides this, two other reasons follow:

because the priests had not sanctified themselves sufficiently;
that is, a sufficient number of them were not sanctified, to slay all the passover lambs the people that came to the feast would want:

neither had the people gathered themselves together to Jerusalem;
they had no notice of it, nor summons for it; and it was required that, at such a time, all the males in the land should appear at Jerusalem; but this custom having been long disused, it required time to acquaint them of the revival of it.

Divrey Hayamim Bais 30:3 In-Context

1 0 And Chizkiyah sent to kol Yisroel and Yehudah, and wrote iggerot also to Ephrayim and Menasheh, that they should come to the Beis Hashem at Yerushalayim, to keep the Pesach Hashem Elohei Yisroel.

2 For HaMelech had conferred and agreed with his sarim, and kol HaKahal in Yerushalayim, to keep the Pesach in the second month.

3 For they could not keep it at its time, because the Kohanim had not set themselves apart as kodesh in sufficient numbers, neither had HaAm gathered themselves together to Yerushalayim.

4 And the thing pleased HaMelech and kol HaKahal.

5 So they established a decree to make proclamation throughout kol Yisroel, from Beer Sheva even to Dan, that they should come to keep Pesach unto Hashem Elohei Yisroel in Yerushalayim, for not many had kept Pesach as prescribed.