I have updated my clients from dnn2 to dnn3 - you must first update to 3.1.0 however the users are not updated. There is a program to update dnn2 users to dnn3 (search the forum and google) I updated the users manually however to do this you will need to set the encryption in the web config file to clear . The program apparently updates the users from msaccess so you need to take the user file from sql to access.

You need to convert the custom modules to dnn3 format before doing the upgrade. I would assume that the reason why you don't see any content is due to the role permissions set for each module - the roles and users were not converted thus this causes a problem - check the updated database and see if the content is there.

once you get the 3.1.0 version running then update to 3.3.5 then to 3.3.7 from there on you are on your own as I have not moved my clients to v4 and probably will not for some time.

If you set the encryption to clear then you can lookup the tables to see what password has been set for the host

lookup aspnet_users this will give you the logon username and the userid then lookup the aspnet_membership for that userid and that will give you the password

apart from this problem of not updating users the rest of the update does work ok. I have however never updated from a multi portal ddn2 to dnn3 but it should still work

I suggest strongly that you do the upgrades offline on your inhouse computer rather then online on the server. once converted then upload the database and code.