How Unhandled Promise Rejections Silently Crash Node.js Background Workers

Unhandled promise rejections are a leading cause of silent failures in long-running Node.js services such as background workers, queue consumers, and batch jobs. A promise rejection is considered unhandled when no .catch() handler, .then() error argument, or try/catch around an await exists anywhere in its chain. Unlike HTTP request handlers where failure is scoped to a single request, a crashing background worker can drop dozens of in-flight jobs with no immediate alert. Modern versions of Node.js have shifted from merely printing warnings to terminating the process outright when such rejections occur. Developers are advised to adopt concrete error-handling patterns to prevent these failures from going undetected in production environments.