The first computer bug was a literal bug.

To be exact, a moth.

On Sept 9, 1947, a moth got trapped in Harvard University's Mark II computer -- causing multiple errors.

This bug disrupted the electronics inside the Mark II.

Here's a photo of that first computer bug.

@atomicpoet i'm curious, is this why the name "bug" was given to computer errors?
The use of "bug" to meant a fault in a system predates that, and was part of the reason that was logged, for being a literal bug rather than only a figurative one.
That's why it says "First actual case of 'bug' being found".