404 errors on IIS6

Make sure that ASP.NET 4.0 is properly registered with IIS 6.0. Run this in the cmd.exe:

c:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet_regiis.exe -i

After that make sure that it is enabled:

Files
Solving problems with on-premises version of Jitbit Helpdesk ticketing system