Windows Server Authentication Error

Conor Lambert 21 Reputation points

Having an issue in our work environment related to Windows Server and .NET Core

Some Background:
We are running a .NET Core 2.1 and Angular 7.3.9 application on our Windows servers.
Our application uses Windows Authentication.

Up until now, all our servers have used Windows Server 2012 R2 and the authentication runs fine for our web application.
However, recently 2 of our servers have upgraded to Windows 2016 and now we are experiencing issues related to Windows Authentication.

Every time we navigate to the website via our browser, we are prompted with login credentials.


Even when we enter our credentials, we are prompted again and again with no luck.

Our IIS Manager settings are the same between 2012 and 2016 environments.

Is there an issue with our .NET Core version?
Or maybe something in our Startup.cs that needs to change in order for the application to work in 2016 environment?

Internet Information Services
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  1. Bruce Zhang-MSFT 3,736 Reputation points

    Hi @Conor Lambert ,

    There could be an issue with security loopback. You can disable it in register.

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

    If you use IE, you can set it to pass credentials automatically. Internet Explorer may prompt you for a password.

    If the answer is helpful, please click "Accept Answer" and upvote it.

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    Best regards,
    Bruce Zhang