Frequently Asked Question

Why can't I navigate to admin.aspx on my IIS Server?
Last Updated 3 years ago

APPLICABLE AUDIENCE: PLATO Intranet Applications, United Kingdom and Australasia.

Platoatlas V10 and Later. (Earlier Platoatlas versions used the deprecated admin.asp.)

IIS Windows authentication through a browser does not work for either Windows Auth or Basic Auth on the IIS machine. Login attempts just fail with a 401 error.

Accessing the same site externally allows access using the same Windows credentials. It only fails when on the local machine.

Loopback Protection on Windows Server

This is caused by Microsoft's Loopback Protection policy that is enabled by default on Windows Servers and more recently in Windows 10, reportedly to prevent local access attacks on the server. The policy disables authenticating against local Windows accounts through HTTP and a Web browser.

This Windows policy cannot be undone or changed by Platoatlas; however, customer IT Administrators can disable the policy by navigating to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa in the affected machine's registry and creating or setting the DisableLoopbackCheck (DWORD) key to 1.

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