Cannot write applicationHost.config

I am trying to deploy an application and I get the following exception

System.Runtime.InteropServices.COMException (0x800719F3): Filename: \?\C:\Windows\system32\inetsrv\config\applicationHost.config Error: Cannot write configuration file

I have many applications already hosted on the same server and have never faced the same issue. I am unable to create AppPool manually as well.

Something that you could do is go to inetpub/history and try using an older file that is not corrupt (you can use notepad++ to compare both for example).

Take care with the modifications directly on the file and the encoding used when editing .. I would recommend doing the changes via GUI or APPCMD/PowerShell to prevent this.