System.DmlException: Insert/Upsert failed. First exception on row 1; first error: INVALID_FIELD, Cannot specify both an external ID reference Parent and a salesforce id, ParentId: []

Hello Trailblazers,

In this post we're going to see the solution of the error "System.DmlException: Insert failed. First exception on row 1; first error: INVALID_FIELD, Cannot specify both an external ID reference Parent and a salesforce id, ParentId: []" OR "System.DmlException: Upsert failed. First exception on row 1; first error: INVALID_FIELD, Cannot specify both an external ID reference Parent and a salesforce id, ParentId: []"

The most common scenario for this error is when we're trying to insert both the parent and child records at the same time and we're providing both - the Salesforce ID of the parent object and the parent object record reference with External ID, mentioned in the child record. Ideally we should only provide one out of Salesforce ID of parent object or parent object reference with External ID but not both. Let's have a look at an example.

Inserting Account and Contact record together

You must be aware of the fact that we can use external ids to create a parent-child relationship automatically while inserting new records in salesforce. For ex: In case of account and contact, you don't need to insert account and then get it's record id to insert contact, in order to link it with earlier inserted account record. You can leverage external id on account to insert both records in a single transaction. Let's see how:

As you can see in the above snippet, I've created a list of sObjects in which I have added one account record and one contact record. I have created an external id field on account with API name as: Reference_ID__c. In case of contact record, I have referred to the parent account record by populating the relationship field "Account" (will be Field_Name__r in case of custom object) with an instance of account object consisting of external id only. Using this we're telling salesforce that this contact is linked to the account with reference id as 123. The above code snippet worked perfectly fine upon execution and as a result, account and contact records are created in salesforce. Give it a try!!

Let's do a very small change now:

As you can see above, now we've also specified AccountId in contact record and that too as null which probably should have no impact. Let's execute the code and see what we get:

As you can see we're getting the same error System.DmlException: Upsert failed. First exception on row 1; first error: INVALID_FIELD, Cannot specify both an external ID reference Account and a salesforce id, AccountId: []. 

As per the post heading error message: "System.DmlException: Insert/Upsert failed. First exception on row 1; first error: INVALID_FIELD, Cannot specify both an external ID reference Parent and a salesforce id, ParentId: []" 

Here our Parent is Account and ParentId is AccountId these can be different depending upon your field name and what objects you're dealing with. This simply means:

"Whenever we're performing a DML on child records, we cannot specify both the parent reference record, as well as the parent record id together, even if the parent record id is null"

So, make sure you're only specifying one of these. That's all for this tutorial everyone, I hope you liked it. Let me know your feedback in the comments down below.

Happy Trailblazing!!