Configuration analysis may display IIS features warnings despite all the relevant features being installed on server. The installer fails to load the Server Manager module (Import-Module ServerManager) which is required to use the Get-WindowsFeature cmdlet used by the installer to check for presence of IIS features.
In this scenario the installer trace may contain the following lines:
">> Command: Import-Module ServerManager Get-WindowsFeature -Name NET-HTTP-Activation Expected Result: Installed System.Management.Automation.CmdletInvocationException: Cannot find drive. A drive with the name 'D' does not exist. ---> System.Management.Automation.DriveNotFoundException: Cannot find drive. A drive with the name 'D' does not exist."
It shows that PowerShell tried to load a module from a non existing drive which is not someting that should happen normally. This happened after the server was restored after an outage, and the D drive was missing - the server had only unpartitioned the disk after the restore. Once we formatted the unpartitioned disk and assigned D drive to it, it fixed the Import-Module cmdlet problem (despite D drive being just an empty disk). This fixed the IIS features warnings and IIS application pool permissions errors.