Troubleshooting 401 Error with Remote Indexes

A 401 error message can appear in the .NET search interface when attempting to connect to a remote index. This may be due to the fact that NTLM is not the default authentication in IIS.

To resolve the 401 error problem in IIS 7

1. Using an administrator account, connect to the Coveo Front-End server.

2. Open the Internet Information Service (IIS) Manager.

3. In the Connections panel, under Sites, select Coveo Enterprise Search 7.

4. In the main panel, double-click Authentication.

5. In the Authentication panel, select Windows Authentication.

6. In the Actions panel, select Provides.

7. In the Providers dialog box, when NTLM is not present in the Enabled Providers list:

   1. In the Available Providers drop-down list, select NTLM, and then click Add.

   2. Click OK.

To resolve the 401 error problem in IIS 6

1. Using an administrator account, connect to the Coveo Front-End server.

2. Open a command line window.

3. Run the following command: cscript adsutil.vbs set w3svc/NTAuthenticationProviders "NTLM"

   Note: Refer to the following Microsoft document for details: How to configure IIS to support both the Kerberos protocol and the NTLM protocol for network authentication.