Even though NAV has been around for many years it seems that people don't know how to do a NAV object update correctly. Agreed... NAV object updates used to be very simple but things have changed when Microsoft introduced the RTC and the Service Tier running on .NET. Back in the days (classic client) it was enough just to import the FOBs and let the user restart the NAV client. Past tense.

Before going into the details let me write down the necessary steps for every NAV object update in NAV2009 RTC and higher:

1. Import FOBs into database
2. Compile the objects
3. Restart the NAV service

If you stop after step one or two... you are basically asking for trouble.
NAV might and will bite you at some point later with unexplainable error messages... many days or weeks after you updated the NAV objects. And because of that you will be looking for the cause of the problem somewhere else.

Yes... according to Microsoft the C# metadata should be automagically recreated after the FOB import but fact is that we had several issues where an error message disappeared after we restarted the service tier.