This Bible contradiction is from the Skeptic's Annotated Bible.

Verses

Michal had no child.

2 Samuel 6:23 View context

Therefore Michal the daughter of Saul had no child unto the day of her death.

Michal had five children.

2 Samuel 21:8 View context

But the king took the two sons of Rizpah the daughter of Aiah, whom she bare unto Saul, Armoni and Mephibosheth; and the five sons of Michal the daughter of Saul, whom she brought up for Adriel the son of Barzillai the Meholathite: