NX Interpart expression issues coming while opening NX9 assemblies in NX11

While opening the NX9 assembly file in NX11 it shows interpart expression message.

Solution

The missing Interpart Expression message customer is getting is not an error, it's a warning message users getting when they load an assembly/part where interpart expression are used and corresponding Part/assembly is not loaded in the current session. If you load those part/assembly then you won't get this warning message.
 
However, if you do not want this message to be appear, then kindly go to File > Utilities > Customer Defaults > Gateway > General > Expressions tab > switch OFF the option "Show Missing Interpart Expression Part Warnings" and Restart NX. Refer below snap for more details.

Notes and References

9244041

Hardware/Software Configuration

Platform: INTL64
OS: window
OS Version: 764SP1
Product: NX
Application: NXMANAGER
Version: V11.0.2
Function: FILE_OPEN

Ref: 002-8007372