Cannot configure ASP.NET for domain in Plesk: Can’t detect .NET version. Possible site does not use ASP.NET

Symptoms

• Configuring ASP.NET settings in Plesk in Domains > example.com > Dedicated IIS Application Pool for Website fails:

  aspnetcfg failed: Can't detect .NET version. Possible site does not use ASP.NET (Error code 1)
  Message aspnetcfg failed: Can't detect .NET version. Possible site does not use ASP.NET (Error code 1)
  File : Agent.php
  Line : 219
  Type : PleskUtilException

• When connected to the server using RDP, the option .NET CLR version is set to No Managed Code in Start > Server Manager > Tools > Internet Information Service (IIS) Manager > server_hostname > Application Pools > example.com(domain)(pool) > Basic Settings.

• Also, the website can not work with the error:

  The page cannot be displayed because an internal server error has occurred.

Cause

In IIS, the option .NET CLR version is set to No Managed Code in the settings of the website’s application pool.

Resolution

1. Log into Plesk.

2. Go to Domains > example.com > Hosting Settings.

3. Disable the option Microsoft ASP.NET support and click Apply.

4. Enable back the option Microsoft ASP.NET support and click Apply.

Note: If you are a domain owner and the option Microsoft ASP.NET support is not shown or not editable, please contact the server administrator or hosting provider for assistance.