"Upholder" experienced a barren run over the next few weeks. Her next patrol, between 23 September and 2 October, was north of Marittimo and stretching to Cape St Vito. Two weeks later, in mid-October 1941, the boat operated with "Urge" in the Kerkenah Bank off Tunisia. On the night of 8 November 1941, lookouts spotted a U-boat in the moonlight off Melito di Porto Salvo. Wanklyn determined it was Italian, possibly a "Perla", "Sirena" or "Argonauta"-class submarine. A full salvo sank the vessel. No survivors were recovered, and only a large oil slick was visible on the surface. "Upholder" picked up the noise of the enemy vessel breaking apart as it sank.