Summary

When you attempt to install the ASP.NET feature in IIS 7.0, you may receive the following error message:

An error occurred. Not all of the features were successfully installed.

Cause

This issue can occur if your computer was upgraded to Windows Vista from an existing Windows XP installation. The upgrade process creates a duplicate ISAPI filter entry. This duplicate entry prevents the ASP.NET installation in Windows Vista from successfully completing.

Resolution

To resolve this issue, follow these steps:

1. To start IIS Manager, click Start, type Inetmgr in the Start Search box, and then click Inetmgr in the Programs list.
2. Expand the local computer node, double-click ISAPI Filters, and then remove all the ASP.NET filters that are listed.
3. Reinstall the ASP.NET feature of IIS 7.0 by using the Turn Windows Features On or Off wizard.

Related Links

Please see the following Microsoft Knowledge Base article for more information.

929772 Error message when you try to install the ASP.NET feature in IIS 7.0: "An error has occurred"