'Too many open files' errors happen when the app exceeds the OS file descriptor limit. Use file streams properly and close resources after usage to avoid this issue.

A 'too many open files' error occurs when your Node.js app tries to open more file descriptors than allowed by the operating system. This usually happens when file resources like streams, sockets, or file handles aren't being closed properly, leading to file descriptor leaks. To avoid this, ensure you’re properly closing files and other I/O resources when they’re no longer needed, either manually or using the finally block in a try/catch statement. You can also increase the OS’s file descriptor limit using ulimit on Linux or macOS. Using connection pools for database connections or file I/O can also prevent this issue by managing resources more efficiently. Properly managing your file descriptors ensures your app runs smoothly without crashing due to system limits.