Recently all of a sudden one of my client started facing an issue that they were unable to get logged in to their CRM. What actually happening was, when the CRM URL was clicked, it asks for the credentials but even after entering the correct userName and Password it was unable to authenticate. After 3 trials it showed the following error:
I Started checking their Microsoft Dynamics CRM Sites in IIS Manager and found out that in Authentication -> Windows Authentication -> Advanced Options -> Enable Kernel-Mode Authentication was unchecked. Maybe accidentally they might have unchecked this option while going through their IIS.
I Re-Checked the “Enable kernel-mode authentication” option and clicked Ok and when this time I opened the CRM URL providing the correct credentials, I was able to view the CRM page.
- Kernel Mode Authentication
IIS (7.0 and later) with Windows Server 2008 enables kernel mode authentication by default. If you’ve installed Microsoft Dynamics CRM using the Network Service account, you’re probably best of enabling kernel-mode authentication.
And when kernel-mode is enabled then it will force IIS to use the machine account. It is recommended to configure that same account used to perform IIS kernel mode authentication, to use the application pool account when configured with a domain account.