Website shows error after upgrading Plesk to Onyx/Obsidian: 500: Cannot add duplicate collection entry of type 'mimeMap' with unique key attribute

Symptoms

• After upgrading Plesk from 12.x version or migrating to Plesk Onyx/Obsidian, a website becomes unavailable with the following error:

  CONFIG_TEXT: HTTP Error 500.19 - Internal Server Error
  The requested page cannot be accessed because the related configuration data for the page is invalid.
  Detailed Error Information:
  Module CustomErrorModule
  Notification SendResponse
  Handler StaticFile
  Error Code 0x800700b7
  Config Error Cannot add duplicate collection entry of type 'mimeMap' with unique key attribute 'fileExtension' set to '.woff2'
  Config File \?\C:\inetpub\temp\apppools\example.com(domain)(4.0)(pool)\example.com(domain)(4.0)(pool).config
  Requested URL http://www.example.com:80/Index.html

• The following error is shown at Windows > Server Manager > Tools > IIS Manager > hostname > Sites > example.com > MIME Types:

  CONFIG_TEXT: There was an error performing this operation.
  Details
  \?\C:\Windows\system32\inetsrv\config\applicationHost.config
  Line number: 2606
  Error: Cannot add duplicate collection entry of type 'mimeMap' with unique key attribute 'fileExtension' set to '.woff2'

• Before upgrading/migrating to Plesk Onyx/Obsidian, the MIME type font/x-woff2 .woff2 was manually added at Plesk > Domains > example.com > IIS Settings > MIME Types.

Cause

Bug ID PPPM-10450, which is planned to be fixed in future updates.
Wrong migrations are applied during the Plesk upgrade.

Resolution

The following workaround is available:

Note: Before applying it, it is very important to note that it will remove any web server customizations previously made on that website.

1. Connect to the server via RDP;
2. Open CMD as administrator and run the following command to delete the website from the web server:

   C:\> C:\Windows\System32\inetsrv\appcmd.exe delete site example.com

3. Recreate the website configuration on the webserver:

   C:\> plesk repair web example.com -y