Answer:
He made a mistake and needed to talk to Dumbledore.
Explanation:
"Harry Potter and the Goblet of Fire" portrays Mr. Crouch as uptight and exacting individual and pure-blood wizard who seems quite indulged in his self-importance and has the ability to practice "fight with fire". Mr. Crouch is quite ambitious and seems obsessed with fighting dark arts yet hunger for power makes him willing to sacrifice his family members in return for his ambitions.
According to the question, when Harry and Krum speaking privately, they saw Mr. Crouch who told them that he had committed a mistake and thus, he required to talk to Dumbledore in this context.
