You may experience a blank, white screen when attempting to use Windows authentication with Safari on Apple iPhone, iPad, or Mac OS X.
This issue is caused by a bug in Safari when both Integrated Windows Authentication (also known as NTLM) and Negotiate Authentication are enabled, and Negotiate Authentication is listed as the first available provider. Under these conditions Safari will enter an infinite loop of Authorization: Negotiate requests and a blank, white page is displayed as a result.
1. Open Internet Information Services (IIS) Manager. In the Connections pane on the left hand side, expand on the Server node. Expand the Sites node. Expand the web site that contains the EmpowerID IIS applications. Click on EmpowerIDWebIDPWindows. In the features view, under IIS, open Authentication.
2. In the Authentication view that appears, click on Windows Authentication. In the Actions pane on the right hand side, click on Providers...
3. In the Providers window that appears, under Enabled Providers, click on Negotiate and click Remove. Click OK when finished.
Detailed technical information regarding this issue can be found on Stack Exchange.
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