This morning I was working on an item for a client when I had to amend the IIS Request Filtering options to allow an application to deploy and after amending the config file, instead of simply restarting the site in IIS, autopilot took over and I performed it from the Powershell cmdlt (IISRESET).
Anyway fast forward 1hr and when trying to view a Web report I was getting an authentication screen popup which strangly was working fine on the server using the same account accessing the same link.
Anyway after a bit of digging it turns out the following items had reset themselves and needed to be changed to allow the access denied box to go away:
Within IIS\[Your Web Site]\Reporting Site
Ensure that under Windows Authentication > Advanced > Enable Kernel-mode authentication is set
Also under providers (Just to the right on the contect menu)
Ensure the Providers are configured as shown:
Ill make sure I use the website restart next time 🙂