Hello,
based on the exception it seems that caption (name) of some node is set to null in database, this causes that configuration wizard fails to load and crashes with this error.
I'd recommend to check if there are any nodes without proper caption in database. If you have Orion SDK installed you can use the SWQL Studio to connect to SWISv2 otherwise, go to the NPM website to a /Orion/Admin/swisv2.aspx page. Then use the following query to see if there are any nodes without valid caption:
SELECT NodeID, Caption, IPAddress FROM Orion.Nodes WHERE Caption IS NULL
Also when exactly does the configuration wizard crash (on which step)?
Let me know if you have any questions.