Error handling

Login page not accessible - Error 500.21

If the logon page does not appear, but instead the HTTP error 500.2.1 is displayed, it is likely that Microsoft .NET Framework 4.8 is not properly installed or registered in IIS.

NOTE: Before you re-register the Microsoft .NET Framework 4.8 on your Internet server, please check that the framework is compatible with any other Internet sites that may be hosted by this server. Back up your system and especially the IIS configuration before you continue.

NOTE: If you have installed NoSpamProxy and Microsoft Exchange on the same server, before installing or upgrading the Microsoft .NET framework, make sure that the appropriate version of the framework is supported by Exchange. For an overview of supported versions, see the Exchange Server Supportability Matrix.

• Re-register the ASP.NET framework with the following command:
  %windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe -i