When attempting to update the Notification Server, the follow error message occured within Symantec Installation Manager when when updating the Product listing:
Symantec Installation Manager has encountered a fatal exception and cannot continue
Log files stated that it is unable write to the Symantec_V2_PL_XML.Zip file.
ITMS 8.x
This was an issue with the folder permissions on the Windows folders.
Security inheritance was not working through all of the levels of the directory structure, breaking the inheritance at the Symantec Installation Manager folder. Changing it to the correct list of accounts allowed the permissions to cascade through the lower levels and then Symantec Installation Manager ran correctly.