[Solved] 401: Unauthorized errors for specific URLs in CRM

Hi all,

Today I faced this issue with one of my CRM instances, where many URLs specific to webresources and other js, css files for CRM were throwing 401 Unauthorized errors, which makes the browser to popup the login window annoyingly. This happens whenever you browse to specific portions in CRM. This may even stop some form event handlers from getting executed.

I tried out different things like reinstalling URL rewrite module, repairing CRM installation but nothing solved the issue. Finally the below configuration change in IIS resolved the issue.

1. Open IIS Manager

2. Select the server node 

3. In features windows, go to Authentication >> Windows Authentication >> Enable.

4. Next select Windows Authentication >> Advanced Settings >> Check the "Enable Kernel-mode authentication" checkbox.

5. Do an iisreset and browse to CRM.

Hope this helps someone.