For legacy debugging on Windows XP (32-bit) only, PortMon remains useful, but Error 2 almost always points to a missing, locked, or misconfigured port – never the tool itself. PortMon Error 2 is not a bug in PortMon – it is Windows telling you that the requested serial port cannot be opened. The error code is a direct pass-through from the CreateFile API.
Start your troubleshooting by verifying the physical or virtual COM port exists and is not locked. If you are on a 64-bit OS or using USB-to-serial adapters, stop immediately and switch to a modern alternative. PortMon was retired for good reason – Error 2 is often the first sign that you have outgrown this legacy tool. Have a legacy system that still needs PortMon? Share your specific error log below – we can help decode the IOCTL stack. portmon error 2
mode com1: baud=9600 parity=n data=8 stop=1 Or use a PowerShell snippet: For legacy debugging on Windows XP (32-bit) only,
If you are a legacy systems administrator, a reverse engineer, or a developer maintaining older Windows applications, you have likely encountered PortMon (PortMonitor). This Sysinternals tool, while retired by Microsoft, remains invaluable for debugging serial and parallel port activity on Windows XP, Vista, and older Server editions. Start your troubleshooting by verifying the physical or