Screen Flows - Exception Handling & Logging - Custom Platform Events Vs Flow Execution Error Event

In the previous post, we saw how to handle and log exceptions in auto-launched flows. In this post let us see Exception handling and logging for screen flows.

For this let us use the below Use case:

Object - Account

Flow Functionality - If the Account type(picklist with values End-User, Partner) is Partner Account – Display a screen to enter additional details by user and based on entered values, decide Account Partnership level(picklist) as Diamond, Gold or Silver. This screen flow will be added to Account record page. Below is the Screen flow which implements this.

Scenario - 1 - Partnership Level Updated Successfully

Add this flow to Account Record page like shown below:

We can make this conditionally visible on the record page by adding component visibility criteria so that screen will be visible only if Account Type is Partner:

Now let us create an Account  - Account ABC with below details:

Name - Account ABC

Active - True

Account Type - Partner

And we can see that, flow component is visible on the screen, and select values from the screen as shown below:

Transaction Behavior

You can see that Partner Level got updated as Diamond

Scenario 2 - Add Validation rule to fail Account Save

Let us add below validation rule in account so that flow update is going to fail.

Transaction Behavior

Execute the flow and you will see an error message on the screen as shown below

Scenario 3 - Add fault Connector and publish Platform event

Like we have done in the previous post of autolaunched flow exception handling, here also let us add a fault connector to publish a platform event and also try to add a custom message to show on the screen instead of standard error message.

Platform event

Publish Platform Event Action in Flow as shown below:

Add User Friendly Error Message Screen

Flow after Adding publish Platform Event and custom error screen:

We have a trigger on Platform event already which process platform event and create Exception record:

Transaction Behavior

You can see custom error message on screen and also an exception record got created:

Exception Record:

Scenario 4 - Log Exception using Flow Execution Error Event

Whenever an exception is happening within a screen flow, Salesforce automatically publish an event to FlowExecutionErrorEvent - which is a standard event. So we can subscribe to this event and log details to Exception record.

As per Salesforce documentetion  FlowExecutionErrorEvent can be subscribed in below mentioned methods:

But Apex Triggers was also supported before and I was able to create a trigger on FlowExecutionErrorEvent, before it was getting disabled:

Or you can also use a process builder to subscribe to FlowExecutionErrorEvent as shown below:

Transaction Behavior

Since we are not handling exception, user will be seeing standard error message on the screen

But Exception details will be logged using PB/Trigger

Comparison between Custom Platform event and FlowExecutionErrorEvent approach for Exception Logging

So we have more flexibility on exception logging if we use custom Platform event. Also I have noticed that FlowExecutionErrorEvent.ContextRecordId is not getting populated like expected in most of the cases.

As of now FlowExecutionErrorEvent is only supported for Screenflows. If that is available for autoaunched flows also, probably then it can be considered as suitable option for exception logging since it is not consuming any governor limits and we don't need custom platform event.

Below is a demo of both approaches:

Resources:

https://developer.salesforce.com/docs/atlas.en-us.platform_events.meta/platform_events/sforce_api_objects_flowexecutionerrorevent.htm

Updating Apex code used below:

Trigger on Platform Event to Create Exception record:

trigger processExceptionPE on Exception_Log__e (after insert) {

    List<Exception__c> ecelist = new List<Exception__c>();

    for(Exception_Log__e ex : Trigger.new){

        Exception__c excep = new Exception__c();

        excep.Object__c = ex.Object__c;

        excep.Operation__c=ex.Operation__c;

        excep.Record_ID__c=ex.Record_ID__c;

        excep.Exception_Details__c =  ex.Exception_Details__c;

        ecelist.add(excep);

    }

    

    if(ecelist.size()>0){

        insert ecelist;

    }

}

Test Class

/************************

* Test class for processExceptionPE

* **********************/

@isTest

public class processExceptionPETest {

    @isTest static void testprocessPE(){

        Test.startTest();  

        Exception_Log__e pe = new Exception_Log__e();

        pe.Object__c = 'Account';

        pe.Operation__c = 'Account Country Population';

        pe.Exception_Details__c = 'Exception happened during process';

        pe.Record_ID__c = 'accid';

        eventBus.publish(pe);

        Test.stopTest();

        List<Exception__c> ex = [SELECT id from Exception__c where Object__c='Account'];

        System.assert(ex.size()>0);

    }

    

}

Trigger On Flow ExecutionErrorEvent to create Exception record:

trigger triggeronflowerror on FlowExecutionErrorEvent (after insert) {

    

    List<Exception__c> ecelist = new List<Exception__c>();

    for(FlowExecutionErrorEvent ex : Trigger.new){

        Exception__c excep = new Exception__c();

        excep.Object__c = ex.ContextObject;

        excep.Operation__c='Populate Account Partnership Level from Floww trigger';

        excep.Record_ID__c=ex.ContextRecordId;

        excep.Exception_Details__c =  ex.ErrorMessage;

        ecelist.add(excep);

    }

    

    if(ecelist.size()>0){

        insert ecelist;

    }

}