The DB Connection keys have changed in 2.0.3.
There are two references to it in previous web.configs, hibernate and the reg. connection string.
Here is how it appears in ours in 2.0.2:
<!-- The SQL Server database connection string -->
<!-- add key="hibernate.connection.connection_string" value="data source=localhost;initial catalog=Gemini;user id=sa;password=sa" -->
<add key="hibernate.connection.connection_string" value="data source=tahiti;initial catalog=bugtracker202;user id=buguser;password=xxxxxxx" />
<!-- Misc -->
<add key="hibernate.connection.provider" value="NHibernate.Connection.DriverConnectionProvider" />
<add key="hibernate.connection.driver_class" value="NHibernate.Driver.SqlClientDriver" />
</nhibernate>
<appSettings>
<!-- DatabaseConnection - The SQL Server database connection string -->
<add key="DatabaseConnection" value="data source=tahiti;initial catalog=bugtracker202;user id=buguser;password=xxxxxx />
Remove the following from your web.config file, and leave ONLY the reference to the hibernate.connection provider:
<!-- DatabaseConnection - The SQL Server database connection string -->
<add key="DatabaseConnection" value="data source=tahiti;initial catalog=bugtracker202;user id=buguser;password=xxxxxx />
I saved the web.config without this extra key, reset IIS and was instantly brought to the site.
I suggest you diligently go through your old and new web.config files and make sure you have one that LOOKS like 2.0.3's. There ARE changes that are NOT documented. I use a great tool called FileCompare which is free at http://www.script-debugger.com/download/fc_setup.exe
Good luck everyone!