R. Jacob b. Benjamin Poppers, Ha'Kohen, was born in Prague, studied under his father and in various yeshivot. He was subsequently appointed rabbi of Coblenz and of Trier, in the Rhineland. He declined an invitation to Halberstadt in 1718 but accepted the rabbinate of Frankfort where he headed a large yeshivah. His disciples included R. Jacob Berlin, R. Joseph Steinhardt, and R. Joseph Wassertrilling. R. Poppers corresponded with the great scholars of his time on halakhic and contemporary problems. He was among those who imposed a ban on R. Moses Hayyim Luzzatto in 1725 for teaching Kabbalah and on suspicion that he adhered to the Shabbatean doctrine. Compelled to leave Italy, R. Luzzatto arrived in Frankfort, where he was summoned before the bet din of R. Poppers and, after much discussion, was obliged again to promise not to teach Kabbalah nor to engage in its study until he was 40 years old.