A bug appeared today but not yesterday. What would you do first?

When a bug surfaces only today, the first step is to isolate the change that introduced it. I would start by reviewing recent commits, deployments, or configuration changes that occurred between yesterday and today. Next, I would reproduce the issue in a controlled environment, using the same data and settings, to confirm it’s not a transient problem. I’d then examine logs, error messages, and stack traces to pinpoint where the failure occurs. If the bug is tied to a specific feature or module, I’d perform a binary search through the code changes to identify the culprit. Finally, I’d document the root cause, apply a fix, and run regression tests to ensure no other functionality is affected. This systematic approach ensures quick identification and resolution while minimizing impact on the rest of the system.