You will require to choose the right ASP.NET for your website in Plesk depends on your website coding. Please refer to the following are the steps to set the ASP.NET support for your website in Plesk.
- Login to your Plesk Panel.
- Click on Websites & Domains.
- Click on Hosting Settings.
- Inside Web scripting and statistics, tick on Microsoft ASP.NET support (Version). Select the appropriate ASP.NET Version and click OK Button. You can select version 3.5 for ASP.NET version 2.0 to 3.5 for select version 4.5 for ASP.NET version 4.0 to 4.5.