The ship was allocated to Group 2 for the Norwegian portion of Operation Weserübung. The group's task was to transport the 138th Mountain Infantry Regiment ("138. Gebirgsjäger Regiment") of the 3rd Mountain Division to seize Trondheim together with "Admiral Hipper", but her machinery broke down again before the troops were loaded and she was replaced by "Friedrich Eckoldt". As part of the post-Narvik reorganization of the "Kriegsmarine"s destroyer forces, "Hermann Schoemann" was assigned to the 6th Destroyer Flotilla ("6. Zerstörer Flotille"). In June the flotilla was tasked to escort the battleships and , as well as the heavy cruiser in Operation Juno, a planned attack on Harstad, Norway, to relieve pressure on the German garrison at Narvik. The ships sortied on 8 June and sank the troop transport , the oil tanker and the minesweeping trawler en route. The German commander, Admiral Wilhelm Marschall, then ordered the "Admiral Hipper" and all four destroyers to Trondheim because of the heavy weather, where they arrived in the morning of 9 June. The two battleships continued the sortie and sank the aircraft carrier and her two escorting destroyers, although "Scharnhorst" was badly damaged by a torpedo from the destroyer in the engagement. The battleship was escorted home by the destroyers "Steinbrinck", "Z10 Hans Lody" and "Hermann Schoemann" for repairs. On 25 June, "Hermann Schoemann" began a lengthy refit that lasted until 15 February 1941, although her machinery continued to be problematic.