You receive an "HTTP Error 401.1 - Unauthorized: Access is denied due to invalid credentials" error message when you try to access a Web site that is part of an IIS 6.0 application pool
When you try to access a Microsoft Internet Information Services (IIS) 6.0 Web site that is configured to use Integrated Windows authentication only, you are prompted for your user credentials. When you try to log on, you receive the logon prompt again. After you try to log on three times, you receive the following error message:
HTTP Error 401.1 - Unauthorized: Access is denied due to invalid credentials.
This behavior may occur if the following conditions are true:
- The IIS 6.0 Web site is part of an IIS application pool.
- The application pool is running under a local account or under a domain user account.
- The Web site is configured to use Integrated Windows authentication only.
If this behavior occurs when the application pool is running under a local account, follow the steps in the "Workaround" section.
To resolve this behavior when the application pool is running under a domain user account, set up an HTTP SPN with the NetBIOS name and the fully qualified domain name (FQDN) of the domain user account that the application pool is running under. To do this, follow these steps on a domain controller:
Important An SPN for a service can only be associated with one account. Therefore, if you use this suggested resolution, any other application pool that is running under a different domain user account cannot be used with Integrated Windows authentication only.
- Install the Setspn.exe tool. To obtain the Setspn.exe tool for Microsoft Windows Server 2003, click the following article number to view the article in the Microsoft Knowledge Base: 970536 Setspn.exe support tool update for Windows Server 2003
- Start a command prompt, and then change to the directory where you installed Setspn.exe.
- At the command prompt, type the following commands. Press ENTER after each command:setspn.exe -S http/IIS_computer's_NetBIOS_name DomainName\UserNameNote UserName is the user account that the application pool is running under. Also note that if you are running the setspn.exe command on a Windows 2000 machine, use the -A switch instead of the -S switch.
setspn.exe -S http/IIS_computer's_FQDN DomainName\UserName
To work around this behavior if you have multiple application pools that run under different domain user accounts, you must force IIS to use NTLM as your authentication mechanism if you want to use Integrated Windows authentication only. To do this, follow these steps on the server that is running IIS:
- Start a command prompt.
- Locate and then change to the directory that contains the Adsutil.vbs file. By default, this directory is C:\Inetpub\Adminscripts.
- Type the following command, and then press ENTER:cscript adsutil.vbs set w3svc/NTAuthenticationProviders "NTLM"
- To verify that the NtAuthenticationProviders metabase property is set to NTLM, type the following command, and then press ENTER:cscript adsutil.vbs get w3svc/NTAuthenticationProvidersThe following text should be returned:
NTAuthenticationProviders : (STRING) "NTLM"
This behavior is by design.
If you set the SPN by using only the FQDN of the server that is running IIS, you will be prompted for your user credentials after 30 minutes. The 30-minute time-out occurs because of the way that Internet Explorer caches Domain Name System (DNS) information. After 30 minutes, Internet Explorer reverts to the NetBIOS name. Therefore, you must make sure that you also register the SPN by using the NetBIOS name of the server that is running IIS to avoid being prompted for your user credentials.For more information, click the following article number to view the article in the Microsoft Knowledge Base:
263558 How Internet Explorer uses the cache for DNS host entriesTo verify the registered SPNs for the user account that your application pool is running under, start a command prompt, type the following command from the directory where Setspn.exe is installed, and then press ENTER:
setspn.exe -l UserNameA list of the registered SPNs for the user account is returned.
Internet Information Services (IIS) 7.0The topics discussed in this article can also apply to IIS 7.0 if one of the following conditions is true:
- Kernel Mode Authentication is disabled.
- Kernel Mode Authentication is enabled, and the useAppPoolCredentials attribute is set to TRUE.
For additional information about using Integrated Windows authentication with IIS application pools, visit the following Microsoft Web site:Note The AuthDiag tool is designed to help you when you see either of the following error messages:
- 401.1 logon failed
- 401.3 ACL
Article ID: 871179 - Last Review: 08/09/2012 03:34:00 - Revision: 7.0
Microsoft Internet Information Services 6.0, Microsoft Internet Information Services 7.0
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