I installed SDL Web 8.5 on Windows Server 2016.

But lots of 401 unauthorized error occurs when connecting to CME.

Login user is Windows' Administorator user. Login succeeds but after that nothing appears on Web browser(CME) and lots of 401 error occurs.Fiddler's image is following.

enter image description here

On IIS's authentication, Windows authentication is enabled as following image.

enter image description here

I tried to add value to registry as following page, but it didn't solve the problem.

SDL Tridion 2013 SP1 The remote server returned an error: (401) Unauthorized On WebUI Core Services Communicator.svc Invoke

I didn't change any configuration after installation. Is any additional configuration required?


  • 4
    I believe those 401 errors are normal and just part of how the web application works, presenting a challenge response to indicate authentication needs to happen. If your CME doesn't work it sounds like something in the installation went wrong or you missed a step. I would suggest trying a repair or an uninstall and reinstall following the steps in the documentation exactly. While it may sound attractive to try and fix this issue manually, it is probably faster to simply retry the install from scratch. Feb 7, 2018 at 8:49
  • I uninstalled IIS from Windows Server, and I installed it again with all roles checked. Then I uninstalled and reinstalled Web8.5, it works. It seems some server roles were missing. Also, 401 errors still occurs while CME is working correctly. Feb 8, 2018 at 11:33

2 Answers 2


Please re-check your CMS system setup and installation steps.

Creating databases for your sample single-machine installation

Running the Content Manager installer for the sample single-machine installation


I saw this once before, this may not be recommended from a security point of view in a production environment, but in your web.config located at <Web 8.5 Home Dir>\web\WebUI\WebRoot add <trust level="Full" /> under <system.web> and all the 401 erors will go away and your Web 8.5 CMS will load up. I think the issue is some permissions you may have missed.

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