You are trying to jumpstart an existing ASP.NET site on a new IIS 7.5 server under Windows 7 or under Windows 2008 R2, and you are getting this error message: Cannot open database “YourDB” requested by the login. The login failed. Login failed for user ‘IIS APPPOOL\DefaultAppPool’. The problem is in IIS 7.5 DefaultAppPool settings. Windows 2008 Server with IIS 7 runs DefaultAppPool using NetworkService user: Windows 7 and Windows 2008 Server R2 with IIS 7.5 run the same pool under a different user – ApplicationPoolIdentity: On the picture above from IIS 7.5 you see a correct setting for DefaultAppPool row. All you need to do is to change that setting…