Nice post that explains hoew to manage exceptions in X++ : https://learn.microsoft.com/en-us/dynamics365/fin-ops-core/dev-itpro/dev-ref/xpp-exceptions
Category: Errors/Issues
AX – D365FO – How to solve error : The Server is unavailable.Check your configuration and network connection and try again.
The Server is unavailable.Check your configuration and network connection and try again. Some time when we try to open the AX this error message appears. The reason for this error message is that AOS service is not started on your machine. Just go to start menu and than search for the services.msc file and than … Continue reading AX – D365FO – How to solve error : The Server is unavailable.Check your configuration and network connection and try again.
AX / Dynamics 365 For Finance and Operations blog 