Applicationhost.config file is deleted and folder is locked.

Hello everyone,

We are facing this critical issue across our entire fleet of Azure VMs and are hoping to share our findings and seek advice.

Summary of the Issue: The applicationHost.config file is being spontaneously deleted, leading to a complete failure of the IIS service. This is a recurring problem that persists even after a full reinstallation of the operating system.

• Windows Server (2022)
• The applicationHost.config file disappears from C:\Windows\System32\inetsrv\config\.
• The parent config directory becomes locked, preventing any manual attempts to copy, restore, or create a new file in its place.
• The issue propagates sequentially across different servers over a period of days.
• Most critically, the problem reoccurs approximately one week after a complete OS reinstallation, indicating the cause is external to the server's base configuration.

We have attempted a wide range of solutions, none of which have permanently resolved the issue:

• Restoring the configuration file from C:\inetpub\history.
• Running file system integrity checks (chkdsk).
• Running OS health and repair commands (SFC /scannow, DISM /RestoreHealth).
• Performing a complete reinstallation of Windows Server.

Any insights from others who have identified the specific root cause or have suggestions for further investigation would be greatly appreciated.Hello everyone,

We are facing this critical issue across our entire fleet of Azure VMs and are hoping to share our findings and seek advice.