This Bible contradiction is from the Skeptic's Annotated Bible.
He was an infant.
Genesis 44:20-22 View context
And we said unto my lord, We have a father, an old man, and a child of his old age, a little one; and his brother is dead, and he alone is left of his mother, and his father loveth him.
And thou saidst unto thy servants, Bring him down unto me, that I may set mine eyes upon him.
And we said unto my lord, The lad cannot leave his father: for [if] he should leave his father, [his father] would die.
He was a grown man with ten sons.
Genesis 46:8-21 View context
And these [are] the names of the children of Israel, which came into Egypt, Jacob and his sons: Reuben, Jacob's firstborn.
And the sons of Reuben; Hanoch, and Phallu, and Hezron, and Carmi.
And the sons of Simeon; Jemuel, and Jamin, and Ohad, and Jachin, and Zohar, and Shaul the son of a Canaanitish woman.
And the sons of Levi; Gershon, Kohath, and Merari.
And the sons of Judah; Er, and Onan, and Shelah, and Pharez, and Zerah: but Er and Onan died in the land of Canaan. And the sons of Pharez were Hezron and Hamul.
And the sons of Issachar; Tola, and Phuvah, and Job, and Shimron.
And the sons of Zebulun; Sered, and Elon, and Jahleel.
These [be] the sons of Leah, which she bare unto Jacob in Padan-aram, with his daughter Dinah: all the souls of his sons and his daughters [were] thirty and three.
And the sons of Gad; Ziphion, and Haggi, Shuni, and Ezbon, Eri, and Arodi, and Areli.
And the sons of Asher; Jimnah, and Ishuah, and Isui, and Beriah, and Serah their sister: and the sons of Beriah; Heber, and Malchiel.
These [are] the sons of Zilpah, whom Laban gave to Leah his daughter, and these she bare unto Jacob, [even] sixteen souls.
The sons of Rachel Jacob's wife; Joseph, and Benjamin.
And unto Joseph in the land of Egypt were born Manasseh and Ephraim, which Asenath the daughter of Poti-pherah priest of On bare unto him.
And the sons of Benjamin [were] Belah, and Becher, and Ashbel, Gera, and Naaman, Ehi, and Rosh, Muppim, and Huppim, and Ard.