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How to Disable the LoopBackCheck in registry

Posted on 22. Nov, 2009 by admin in Others

If you receive error 401.1 when you browse a Web site that uses Integrated Authentication and is hosted on IIS 5.1 or a later version

error:

HTTP 401.1 – Unauthorized: Logon Failed

also if you check your IIS logs for your site you will find  401.2 and 401.1 errors for your requests, then you need to disable the LoopBackCheck key in registry and restart your Server.

To set the DisableLoopbackCheck registry key, follow these steps:

1. Click Start, click Run, type regedit, and then click OK.
2. In Registry Editor, locate and then click the following registry key:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
3. Right-click Lsa, point to New, and then click DWORD Value.
4. Type DisableLoopbackCheck, and then press ENTER.
5. Right-click DisableLoopbackCheck, and then click Modify.
6. In the Value data box, type 1, and then click OK.
7. Quit Registry Editor, and then restart your computer.

Tags: 401.1, 401.2, CurrentControlSet, Disable, DisableLoopbackCheck, error, HTTP 401.1, IIS, Integrated Authentication, key, Logon Failed, registry, Unauthorized