I got this error today
NAV/CRM Dynamics Connector – Object reference not set to an instance of an object
this was very frustrating because I hadn’t changed anything, literately tried to turn on the connector to make some changes.
I’m not sure what had happened but the connector had got itself into a right mess. I tried to repair it and it couldn’t write any values to the MSDI database.
It was complaining about the user privileges but the user had admin rights on the machine and the database.
I tried uninstalling and reinstalling but this didn’t work at all because then the service was appearing in the list of services, the database was still dodgy.
In the end to resolve this problem I had to delete the MSDI database in SQL Server management studio.
What I surmise was the problem was the database had for some reason become corrupted and if you don’t delete the database I think it still leaves it there to use, so when I reinstalled the connector it was still using (or trying to) the corrupted database.
I did find a couple of other blog posts which put forward different answers but they seemed like more effort than deleting and starting again (make sure you back up those maps)
but I will paste them below if you need to try them
this one seems quite promising but it didn’t work for me