Upgrading existing RC2 Sites to RC3
There are some issues in upgrading from an RC2 site to RC3. To work around this, follow these steps:
Install the RC3 core files via the manager, do not install any module.
Modify the virtualPath providers in the RC3 site's web config.
Change the name attribute of each provider so that it matches a provider in the RC2 site's web.config. Add new providers in the RC3 site's web.config if needed. Note that the VirtualPathNativeProvider provider type has been removed in RC3, the only existing type is VirtualPathVersioningProvider.
Set pageStartId="1" in the RC3 site's web.config.
Go to admin mode on your RC2 site and select Export Data from the Admin tab.
Check Export pages and select the startpage as the root of the export. Check Export globalized pages and Automatically export dependent page types.
Check all dynamic properties, all tabs and all categories.
Click the Export button and save the file locally.
Go to admin mode on your RC3 site, note that you have to enter the complete address manually [http://yourHost/(yourVirtualDir)/yourUIFolder/admin].
Select Import Data from the Admin tab, select your exported package and select the Root page as page destination.
Click the Begin import button and wait for the process to finish.
Copy all project files from your RC2 site to your RC3 site, this includes all your templates and controls, the .csproj file and the compiled project assembly.
Please report any problems in this process on the EPiServer CMS support forum.