A REST API is created with XData, and the front-end page is being linked to TMS Web Core.
I encountered a problem that the REST API server abnormally terminated when AAA API was called from 60 front-end pages at the same time. Is it possible to debug an abnormally terminated REST API server by looking at any part of the XData settings?
I don't think it's possible to debug an abnormal termination of any Delphi application, regardless if it's a REST API or regular desktop application. If it's terminated, it can't be debugged.
I'd start by logging the request to have an idea if it's a specific endpoint is being called frequently before the termination, so you might guess some specific endpoints are causing it.
Check the Windows event system to see if you have some log made by Windows related to your application, sometimes Windows itself logs an error in the event system.
Also, do some stress tests to your REST server, i.e., create an application - or use specific tools like JMeter - that simulates such high load in your server, requesting similar endpoints as your front end are invoking, so you might be able to reproduce the issue in a controlled environment.
Finally, is your application using databases? Check how is your database behaving, check its logs, if possible check how many connections are being created to the database specifically. Maybe your connection pool is not properly configured, or there are too many connections to the database, etc..