IIS Web Platform Installer Error: 'doctype' is an unexpected token. The expected token is 'DOCTYPE'. Line 1, position 3

I've just created a new IIS website on a Windows Server 2008 in order to use it to deploy a new website.
The website is still empty.

If I try to open IIS Web Platform Installer under Management Tools, I get stuck on the error:

'doctype' is an unexpected token. The expected token is 'DOCTYPE'. Line 1, position 3.

After closing the error, the Web platform Installer closes.

Do anyone know how to solve it?

Let me know in the comments if you need any other info or technical data, I have really no idea on how can I troubleshoot this

Done, here's how I solved.

This issue seems to be strictly related to an old configuration of this server, so I had to manually reset it. If you face this issue, these following steps should work fine:

• First of all, I had to remove the IIS role functionality from Control Panel > Programs and Features > Turn Window Features on or off > Roles.
• Then, I restarted the server and added again the IIS role functionality (make sure to check all of the asp net functionalities).
• After that, I restarted the server (again) and I have reinstalled:
  1) DotNetCore.2.0.7-WindowsHosting (you've got to find the installer online, make sure to download the last version. 2.0.7 was the last when I made this question so on 25/05/2018)
  2) Web platform Installer from here.
• Executing web platform installer from all program inside start menu worked fine.

Hope it will be helpful

(See Also: How to Install Web Platform Installer and Web Deployment)