‘A blessing in disguise’ is commonly heard in both social and professional situations and refers to the idea that something that appears to be a misfortune can have unexpected benefits. A ‘blessing’ is a prayer asking for a gift from the heavens, and a disguise conceals the real identity of something. So, this idiom is something positive which is concealed to look like something negative.
Further Examples:
The lady fell over in the street, but it was a blessing in disguise because the man who helped her up turned out to be her future husband.
Losing out on the promotion was a blessing in disguise, because he upskilled and eventually got an even bigger promotion.