This application domain-wide event provides a mechanism to prevent exception escalation policy (which, by default, terminates the process) from triggering.

To make it easier for developers to write asynchronous code based on tasks, the net_v45 changes the default exception behavior for unobserved exceptions. Although unobserved exceptions still raise the TaskScheduler.UnobservedTaskException exception, the process does not terminate by default. Instead, the exception is handled by the runtime after the event is raised, regardless of whether an event handler observes the exception. This behavior can be configured. Starting with the net_v45, you can use the <ThrowUnobservedTaskExceptions> configuration element to revert to the behavior of the net_v40_long and terminate the process:

<configuration> 
   <runtime> 
      <ThrowUnobservedTaskExceptions enabled="true"/> 
   </runtime> 
</configuration>