I have an old Win XP machine inherited from a neighbour. We use it to play videos on our TV. Microsoft issued a bug fix against the Wannacry ransomware attack, the one that encrypts your data, for Win XP SP3.
I downloaded the bug fix and only then found out that the Win XP Home edition, which I have, is excluded. I have Win XP SP3, just not the right Win XP SP3.
Great.