Hi,

I have no idea where my error is, debug log message is "System.NullPointerException: Attempt to de-reference a null object"  and error titled "Insert failed. First exception on row 0; first error: CANNOT_INSERT_UPDATE_ACTIVATE_ENTITY, updateContactsOnAddressChange: execution of BeforeInsert" 

I guess I'm confused because because of my trigger before insert and after update.

Any help appreciate it!

This is my trigger: 

trigger updateContactsOnAddressChange on Account (before Insert, after update) {
     
        // I want to find the new address/values on Account by map Id Keys 
         
        Map<Id, Account> acctsWithNewAddresses = new Map<Id, Account>();
     
        // Trigger.new holds my list of the Accounts that will be updated        
        // This loop iterates over the list, and adds any that have new
        // addresses to the acctsWithNewAddresses map. 
         
        for (Integer i = 0; i < Trigger.new.size(); i++) {
            if (   (Trigger.old[i].BillingCity != Trigger.new[i].BillingCity)
                || (Trigger.old[i].BillingCountry != Trigger.new[i].BillingCountry)
                || (Trigger.old[i].BillingPostalCode != Trigger.new[i].BillingPostalCode)
                || (Trigger.old[i].BillingState != Trigger.new[i].BillingState)
                || (Trigger.old[i].BillingStreet != Trigger.new[i].BillingStreet))  {
                acctsWithNewAddresses.put(Trigger.old[i].id,Trigger.new[i]);
            }
        }
                         
        List<Contact> contacts = [SELECT id, accountid, MailingCity, MailingCountry, MailingPostalCode,MailingState, MailingStreet
                          FROM Contact
                          WHERE accountId in :acctsWithNewAddresses.keySet()];
            
                    List<Contact> updatedContacts = new List<Contact>();
     System.debug('Kellers ' + contacts);


        //iterating over each contact in Account
        for (Contact c : contacts) {
            Account parentAccount = acctsWithNewAddresses.get(c.accountId);
            c.MailingStreet = parentAccount.BillingStreet;
            c.MailingCity = parentAccount.BillingCity ;
            c.MailingCountry = parentAccount.BillingCountry ;
            c.MailingPostalCode = parentAccount.BillingPostalCode ;
            c.MailingState = parentAccount.BillingState ;
            c.MailingStreet = parentAccount.BillingStreet ;
    
     
         // Rather than insert the contacts individually, add the         
            // contacts to a list and bulk insert it. This makes the         
            // trigger run faster and allows us to avoid hitting the         
            // governor limit on DML statements 

            updatedContacts.add(c);
        }
        update updatedContacts;
    }

 This is my test: 

@isTest
public class TestUpdateContactsOnAddressChange{
    static testmethod void testAddressChange() {
       //create an account and create account address
        Account sAcct = new Account();
       	sAcct.Name = 'Test Account';
        sAcct.BillingStreet = '11 Initial Street'; 
        sAcct.BillingCity = 'Rochester';
        sAcct.BillingPostalCode = '12456';
        sAcct.BillingState = 'NY';
        sAcct.BillingCountry = 'USA';
       	 insert sAcct;
       	
                
        //create contact for Account "Test Account" and create contact address
        Contact[] sContact = new Contact[]{
        	new contact(
        MailingStreet = '1 Initial street',
       	MailingCity = 'Rochester',
        MailingPostalCode = '12456',
        MailingState = 'NY',
        MailingCountry = 'USA',
        accountid = sAcct.id),
                
        	new contact(
        MailingStreet = '2 Initial street',
        MailingCity = 'Rochester',
        MailingPostalCode = '12456',
        MailingState = 'NY',
        MailingCountry = 'USA',
        accountid = sAcct.id),
       
        	new contact(
        MailingStreet = '3 Initial street',
        MailingCity = 'Rochester',
        MailingPostalCode = '12456',
        MailingState = 'NY',
        MailingCountry = 'USA',
                accountid = sAcct.id) };
       
        insert sContact;
        
        //change address on account
        sAcct.BillingStreet = '11 Updated Street'; 
        sAcct.BillingCity = 'Updated City';
        sAcct.BillingPostalCode = '99999';
        sAcct.BillingState = 'PA';
        sAcct.BillingCountry = 'Mexico';
          
        Test.startTest();
         update sAcct;//this should fire my trigger.
        Test.stopTest();
             
               
        sContact = [Select id, accountid, MailingStreet, MailingCity,MailingPostalCode, MailingState, MailingCountry from 
                     contact where id in: sContact];
        
        //check if account updated address match each contact address
       	System.assertEquals(sAcct.BillingStreet, sContact[0].Mailingstreet); 
        System.assertEquals(sAcct.BillingCity, sContact[0].MailingCity); 
        System.assertEquals(sAcct.BillingPostalCode, sContact[0].MailingPostalCode); 
        System.assertEquals(sAcct.BillingState, sContact[0].MailingState);
        System.assertEquals(sAcct.BillingCountry, sContact[0].MailingCountry);
        
        //check addresses didn't match before update
        System.assert(sContact[1].MailingStreet != sAcct.BillingStreet); 
        System.assert(sContact[1].MailingCity != sAcct.BillingCity); 
        System.assert(sContact[1].MailingPostalCode != sAcct.BillingPostalCode); 
        System.assert(sContact[1].MailingState != sAcct.BillingState);
        System.assert(sContact[1].MailingCountry != sAcct.BillingCountry);
        
    }
}

 noobfn