Updated: July 11, 2016
This article provides solution on the issue when upgrading NPM on APE (Additional Polling Engine) server to version 12 detecting that the SRM version is incompatible.
Even after uninstalling SRM 6.1 and rebooting the APE server the issue still persists. This is due to the SRM 6.1 registry remnant on the server registry.
Warning: Make sure to back up your windows registry first before applying the solution.