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

"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"

Hello Trailblazers, in this post we're going to talk about the resolution of a very common error as given below:

First error: Exceeded max size limit of 12000000 OR First error: Exceeded max size limit of 6000000 

This error appears when you've exceeded the heap size limit in a single transaction. The heap size limit for a synchronous transaction is 6MB and for an asynchronous transaction is 12MB. Asynchronous transactions basically consists of batch classes, future methods and queueable apex.

How to resolve this error?

List<Account> accounts = [SELECT Id FROM Account];
// Stores 50,000 records at max - greater heap size

for(List<Account> accounts : [SELECT Id FROM Account]) {
}
// Stores 200 records at max - lesser heap size

4. Manage your code effectively using helper functions - Avoid class level variables.

void callMe()
{
    List<Account> accounts = [SELECT Id FROM Account];
    System.debug(Limits.getHeapSize()); // Coming as: 321085
}
callme();
System.debug(Limits.getHeapSize()); // Coming as: 1044