We have an existing DNN 5.02.02 site running on Server 2003, IIS 6, SQL 2005 that we want to move to Server 2012 IIS 8.  DB will remain SQL 2005 for now.

I can get it to start loading but it fails in the Initialize.Init(app) step in the Global.asax.vb module with the following error: "System.Security.SecurityException: Request for the permission of type 'System.Data.SqlClient.SqlClientPermission, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed."

I have another ASP.NET web app on an identical virtual copy of this server, which accesses the same SQL server just fine.

App Pool is v2.0 Classic Pipeline with 32 bit enabled. I have tried standard App Pool Identiy and I have also setup a service account  that is a member of the IIS_IUSRS group. I have tried adding Full Trust parameter in the web.config file.  Any thoughts would be appreciated.  Thanks!

Sebastian - Thank you for your quick reply.  SQL connection was not an issue.  I did a fresh install of v 6.2 without any problems pointing to the same SQL 2008 server our v5 portal was attached.

Since that new install went so well, I took a chance and exported 200 pages from the v5 portal and created a new v6 portal by importing the content.  It took 2 tries to do this, because I did not have all of the custom modules installed the first time around.  After the import I did nave to manually fix about 40 page links and I had 10 console controls that needed to be redefined.

Overall I spent 6 hours doing the complete conversion, but everyone is very happy with the outcome.  So now we have DNN v6.2 running under ASP.NET 4.0 on a Windows 2012 server running IIS 8 that is attached to an SQL 2008 Release 2 database. 

If only our legacy VB6 / SQL 2000 applications could upgrade this smoothly ...