True or False: When using upsert(), all records must be of the same sObject type.

The statement is true because the upsert() operation in Salesforce is designed to either update existing records or insert new records based on a specified unique field. This means that when using upsert(), the operation is limited to records of a single sObject type.

Each sObject type in Salesforce, such as Account, Contact, or Custom Objects, has its own unique set of fields and behaviors. Therefore, when you attempt to perform an upsert operation, all records must belong to the same sObject type to ensure that the Salesforce platform can correctly interpret which fields to check for existing records and which fields to populate in new records.

This constraint is important for maintaining data integrity and ensuring that operations are executed without errors. Attempting to mix records from different sObject types would lead to confusion and potential failures in the operation, as the system would not be able to reconcile the diverse structures and rules governing those objects.

Using upsert with different sObject types is not valid and would be rejected by Salesforce. Thus, the requirement that all records must be of the same sObject type is a fundamental aspect of the upsert() function.