If you are on Windows 7 (32-bit or 64-bit) or 8.1, the original Portmon may work if you enable legacy features:
Now that we've explored the causes and symptoms, let's move on to the solutions. Try these troubleshooting steps to resolve the portmon.exe error 2: portmon.exe error 2
With the right plugins, it can monitor USB-to-Serial traffic. Serial Port Monitor (Eltima/Electronic.us): A robust, professional-grade paid alternative. Device Monitoring Studio: Another powerful tool for tracking data bits across ports. Termite or PuTTY: If you are on Windows 7 (32-bit or 64-bit) or 8
Because Microsoft abandoned Portmon, the community created a patched version. Users "Henry Gabryjelski" and others reverse-engineered Portmon to remove the broken driver install routine and replace it with a compatibility shim. Device Monitoring Studio: Another powerful tool for tracking
If you are reading this, you have likely double-clicked your trusty Portmon.exe file only to be met with a cryptic message:
Do not panic. This article dissects exactly what Error 2 means, why it happens, and the four verified methods to fix it—including a modern alternative.
The engineer switched to Serial Port Monitor by Eltima in trial mode. Within 10 minutes, they captured the full hex dump of the CNC traffic, resolved the baud rate mismatch, and fixed the machine. They never looked back at Portmon.