King James Version
And this was the cause that he lifted up his hand against the king: Solomon built Millo, and repaired the breaches of the city of David his father.English Standard Version
And this was the reason why he lifted up his hand against the king. Solomon built the Millo, and closed up the breach of the city of David his father.New International Version
Here is the account of how he rebelled against the king: Solomon had built the supporting terraces and had filled in the gap in the wall of the city of David his father.