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 Sorry, this one’s an urban legend, have a read of https://ourplnt.com/first-computer-bug/. The term has been used for a lot longer than that.
The first "actual" computer bug was found on September 9, 1947 - Our Planet

On Sep. 9, 1947, programmers traced an error and found a moth trapped in a relay. Some say this was the first case of a computer bug, but it's not true.

Our Planet