In 2 Corinthians 2:13, Paul had no peace at Troas because he did not find whom there?

Answer: Titus

Though a door stood open at Troas, Paul had no peace because he did not find his brother Titus there, so he went on to Macedonia.

“Now when I went to Troas to preach the gospel of Christ and a door stood open for me in the Lord, I had no peace in my spirit, because I did not find my brother Titus there. So I said goodbye to them and went on to Macedonia.”— 2 Corinthians 2:12-13 (BSB)