HTTP Error 401 – Not Authorized Error in SharePoint site with Kerberos Authentication Enabled

In a new SharePoint web application, it prompted for user name and password repeatedly

401 not authorized sharepoint 2010
And finally resulted in  “Not Authorized – HTTP Error 401. The requested resource requires user authentication” – in the SharePoint site with Kerberos Authentication Enabled.

sharepoint 401 not authorized

Here is some more spec: MOSS 2007, Windows 2008, IIS 7.5.


With IIS 7.5, Kerberos enabled for SharePoint, we must turn OFF the “Kernel Mode Authentication”. Here is how:

1. Open the IIS, Select the authentication feature of the appropriate web application

sharepoint 2010 kerberos 401 unauthorized

2. Select the authentication mode which is enabled, click on Advanced settings

3. Make sure you have unselected the “Kernel Mode Authentication”

sharepoint kerberos 401 unauthorized

4. Do an IISReset

Salaudeen Rajack

Salaudeen Rajack - Information Technology Expert with Two-decades of hands-on experience, specializing in SharePoint, PowerShell, Microsoft 365, and related products. He has held various positions including SharePoint Architect, Administrator, Developer and consultant, has helped many organizations to implement and optimize SharePoint solutions. Known for his deep technical expertise, He's passionate about sharing the knowledge and insights to help others, through the real-world articles!

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