What's wrong?

ERROR

This four-letter term often appears in red on a computer screen when something goes wrong during code execution.

The clue "What's wrong?" is a straightforward definition hinting at something that’s incorrect or mistaken. The answer "ERROR" fits perfectly because it’s a common term for a mistake, especially in computing or general usage. There’s no hidden wordplay here—it’s a direct question expecting a simple, precise response. Think of it like a tech support agent asking what’s malfunctioning and getting "error" as the reply.