We are upgrading Enterprise from 10.7.1 to 10.8.1. Our Portal environment uses portal tier authentication. When I installed web adaptor for portal I got this when trying to configure it:
"Error message 401.3: You do not have permission to view this directory or page using the credentials you supplied (access denied due to Access Control Lists). Ask the Web server's administrator to give you access to 'C:\inetpub\wwwroot\portal\webadaptor\WebAdaptor.aspx'."

After some pain I found that granting full access to IUSR the web adaptor folder fixed the issue.
https://stackoverflow.com/questions/10418669/hosting-asp-net-in-iis7-gives-access-is-denied
Is the IUSR supposed to have full access to the web adaptor folders with portal tier authentication?