Cannot create subdomain in Plesk: This website cannot be started. Another website may be using the same port

Symptoms

• Cannot create subdomain in Plesk:

  PLESK_ERROR: Error: This website cannot be started. Another website may be using the same port.
  In Microsoft.Web.Administration module
  Exception type: Microsoft.Web.Administration.ServerManagerException
  at Microsoft.Web.Administration.Site.Start()
  at IISWebSite.startStop(IISWebSite* , Boolean start)
  at IISWebSite.start(IISWebSite* )
  at setServerState(true, true)(WebServerAdapter::setServerState line 2331)
  at configHosting(apiged.atoscapital.com.br)(WebServerAdapter::configHosting line 422)
  at configHosting(apiged.atoscapital.com.br)(WebServerManager::configHosting line 2856)
  at Unable to execute console command: '--install-vhost'(vconsoleapp::start line 95)
  at Unable to execute command: '"C:\Program Files (x86)\Plesk\admin\bin64\websrvmng" --install-vhost "--vhost-config=C:/Program Files(x86)/Plesk/PrivateTemp/iah89427101.tmp"'(vconsoleapp::run line 117)

• Websites in IIS are stopped and cannot be started with the following error:

  CONFIG_TEXT: (Exception from HRESULT: 0x80070020)

Cause

Port 443 listening by another application:

C:\> netstat -ano | findstr ":443"
TCP 0.0.0.0:8443 0.0.0.0:0 LISTENING 2804

Resolution

1. Connect to the server via RDP
2. Find the application that listens 443 port by its PID in Resource Monitor and stop/reconfigure it
3. Open cmd.exe as administrator
4. Restart IIS:

   C:\> iisreset

5. Reconfigure webserver:

   C:\> plesk repair web