1. Login to Plesk control panel.
2. From Server components (Tools & Settings >> Server Management >> Server components) identify the ASP.NET versions installed in the server.
3. Select the desired domain from "Domains" tab.
4. Select 'Show Advanced Operations' from 'Websites & Domains' tab.
5. Select 'Web scripting & Security' option.
6. Select the desired version from 'Microsoft ASP.NET support' drop down menu under 'Web Scripting and Statistics'.
7. Click 'Ok' button.