[BUG] IIS WS2016->WS2019 upgrade error
I did an upgrade in situ from Windows Server Standard 2016 with GUI to 2019. All went well except IIS. On upgrading the Default Site the installer added two files iisstart.htm and iisstart.png. Having priority of Default Document of iisstart.htm higher then Default.aspx my Default Web Site lost its main page which is a nasty experience. Changing order in IIS Manager was enough.
A bigger bug was to change the permission of c:\inetpub\wwwroot - DefaultAppPool was removed from permissions. When I added back "IIS AppPool\DefaultAppPool" to permissions, all came back to normal.
I know that upgrade with apps is not recommended, but I had no time to pass through all installation.
Please remove this erratic installer behaviour from Sept 2019 version of the installation.