When attempting to convert the units of a recently opened IGES file using ug_convert_part utility, NX was complaining that the file was from a newer version.
Solution
If you have multiple versions of NX installed - you have likely launched an incompatible (earlier) version of the NX Command Prompt by mistake.
Open the file to be converted and use Menu-> Information-> Part-> Part History to determine the NX Program version it was last saved in.
Launch the NX Command Prompt ( Siemens NX-> Tool - NX Command Prompt) to ensure the correct environment variables are in place when executing the ug_convert_part utility.
Notes and References
Hardware/Software Configuration
Platform: INTEL
OS: windows
OS Version: 1064
Product: NX
Application: GATEWAY
Version: V1847
Function: UNITS
Ref: 001-9538503