This error showed up for me whilst trying to access the SSRS localhost web page on a Windows 10 Enterprise x64 system.
The usual fix is to use the SSRS server configuration page (http://localhost/reports_REPLACE_HERE_WITH_YOUR_SQL_ENGINENAME):
- Click on the “Site Settings” link (top right) followed by “Security” (left hand side menu) and add the needed domain user account as a System User.
- Then go back to “Home” (top left) and using the “Folder Settings” button add a “New Role Assignment” for the needed domain user account having a minimum of “Browser” and “Content Manager” permissions.
However on Windows 10 systems the (now standard) Edge browser can’t be Run as Administrator, and also can’t be run from the Administrator account (if you want to enable it from a Powershell (as Admin) prompt with: net users Administrator /active:yes).
So the solution for me was to install another browser, Google Chrome per se, Run that one as Administrator and do the ‘usual fix’ as explained above, after which the SSRS site will work as expected (from the -now standard- Edge browser window).
PS @MSFT: there seems to be a hidden agenda on behalf of Microsoft’s product team for this implementation and whilst I’m not on the inside of it I hope one day the reasoning will transpire