Glück im Unglück

Literally, “good luck in bad luck”.

Glück im Unglück(e) n

1. a positive occurrence or coincidence that alleviates a mishap or accident; a situation where “it could have been worse”

   Wir hatten Glück im Unglück, weil die Gegenfahrbahn frei war. Sonst wären wir jetzt tot.

   It was lucky that the oncoming lane was empty. Otherwise we’d be dead now.

   (literally, “We had good luck in bad luck because the oncoming lane was empty. [...]”)

2. blessing in disguise (less often and only when the good occurrence outweighs the bad)

   Es war Glück im Unglück, dass ich mir das Bein gebrochen habe, denn sonst hätte ich meine Frau nie kennen gelernt.

   It was a blessing in disguise that I broke my leg, because otherwise I’d have never met my wife.