Contradiction with Exodus 12:6
Exodus specifies the Passover lamb should be killed on the 14th day, not the 15th as implied.
Exodus 12:6: And ye shall keep it up until the fourteenth day of the same month: and the whole assembly of the congregation of Israel shall kill it in the evening. [in...: Heb. between the two evenings]
Contradiction with Numbers 9:5
Passover was observed in the first month, but 2 Chronicles 30:15 refers to the second month.
Numbers 9:5: And they kept the passover on the fourteenth day of the first month at even in the wilderness of Sinai: according to all that the LORD commanded Moses, so did the children of Israel.
Contradiction with Deuteronomy 16:5-6
The Passover sacrifice should be done at the place God chooses, not necessarily Jerusalem as done here.
Deuteronomy 16:5-6: Thou mayest not sacrifice the passover within any of thy gates, which the LORD thy God giveth thee: [sacrifice: or, kill]
Contradiction with Leviticus 17:3-4
Sacrifices must be offered at the entrance of the tent of meeting, contrary to the open locations in Chronicles.
Leviticus 17:3-4: What man soever [there be] of the house of Israel, that killeth an ox, or lamb, or goat, in the camp, or that killeth [it] out of the camp,
Contradiction with Numbers 28:16-17
Passover is mandated on the 14th day of the first month, contradicting the second month observance.
Numbers 28:16-17: And in the fourteenth day of the first month [is] the passover of the LORD.