Hebrews 9:7

But into the second [went] the high priest alone once every year. Into the second part, the Most Holy Place, none entered but the high priest alone, he only once a year at the feast of the atonement, and then carrying the blood of the atonement, which he offered for his own sins as well as those of the people. See Le 16:11-15 Ex 30:10-25.

The errors of the people. Their sins of ignorance and mistakes. High handed, open defiance of God's law was not atoned for. See Le 4:2,13,22,27.
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