In about 15 years of being a developer, I have met a lot of difficult bugs in all categories of this list. But there is another kind of bug that happened to me

In about 15 years of being a developer, I have met a lot of difficult bugs in all categories of this list. But there is another kind of bug that happened to me only 3 times so far, and that I definitely consider it to be the hardest of all. It's when the language interpreter/compiler itself is broken. This is a nightmare to find and understand because when it happens, nothing makes sense. You can take a break, have a whole night of sleep, have a walk or talk to a rubber duck, it still does not make sense because the logic itself is broken.