After installing Exchange 2016 CU9, most of our websites stopped working and we are getting the error:
Access denied. You don't have authorization to view this page.
HTTP ERROR 403
We also noticed our web.config file was missing data and the url rewrites were also gone in IIS. We tried restoring the web.config file from a backup. It did bring back the url rewrites in IIS, but we are still getting the access denied error when trying to browse to the website.