Upvote:6
It is known. Just the English Wikipedia does not mention it. The German one does:
Shortly before the end of the war, February 8 1945, in Nymphenburger hospital in Munich.
Confirmed by a more reliable source, like
— Stolberg-Wernigerode, Otto zu: Neue deutsche Biographie, Bd.: 12, Kleinhans - Kreling, [Schriftleitung Hauptschriftl. Fritz Wagner ... Genealog. Beratung Friedrich Wilhelm Euler], Berlin, 1980. (link)