Question: How to fix Service Unavailable error on HC login page ?

Solution:
The possible reason for this error, "Service unavailable" could be that .NetFramework is failing in IIS. To verify this, please:

1. Go to IIS :: Websites :: properties :: ISAPI filter, you will see ASPNET 2.0 filter, if it is showing in RED down Arrow. Then Remove it and restart IIS.
2. Check if HC website is running under ASPNET 2.0 version.

Go to IIS :: Websites :: Hosting Controller :: Properties :: ASPNET tab. There make sure that .NET 2.0 version is enable/selected. 

    If above suggestions didn't help, then follow this:

Open command prompt, select path
C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727

Execute command
aspnet_regiis.exe -i

This would fix the problem but if it persists, then contact HC Support department at support@hostingcontroller.com for further assistance.