I followed the following steps to upgrad my SharePoint 2010 web application to SharePoint 2013 Preview:
- Backup SharePoint 2010 Content DB
- Restore it on SharePoint 2013 Preview SQL server 2012
- Run the command Mount-SPContentDatabase from PowerShell
- Browse my web application
- I found the following error
The context has expired and can no longer be used. (Exception from HRESULT: 0x80090317)
After that everything workfine.