Where: This change applies to Lightning Experience and Salesforce Classic.
How: The BatchApexErrorEvent object represents a platform event associated with a failing batch Apex execution. To fire this platform event, a batch Apex class declaration must implement the Database.RaisesPlatformEvents interface. A BatchApexErrorEvent platform event is fired when a batch Apex job encounters an unhandled exception. For more details, see Firing Platform Events from Batch Apex in the Apex Developer Guide.