Overview
Cannot invoke "java.util.List.iterator()" because the return value of "java.util.Map.get(Object)" is nullThis error can occur when Payments2Us attempts to create Gift Transaction records in Salesforce Nonprofit Cloud using the Business Process APIs. Because the Salesforce API response is generic, the Error Log and related Payment Txn records should be reviewed to identify the specific data issue.
If you see the following error in the Error Log, this article applies:

Common Causes
Cause 1: Missing or invalid email address
The email address on either the Payment Txn or the related Contact record may be missing or invalid.
Cause 2: Inconsistent “Donation By” details
The Payment Txn may have Donation By set to Individual, but one of the following fields is also populated incorrectly:
- Donation By Name
- Account
Resolution
- Open the related Error Log records.
- Review the related Payment Txn Ids listed in the Error Logs.
- Check each affected Payment Txn and confirm:
- The email address is populated and valid.
- The related Contact has a valid email address, where applicable.
- The Donation By, Donation By Name, and Account fields are consistent.
- Correct the data as required.
- Update the Payment Txn status back to: NPC Processing Start
Once the data has been corrected and the status is updated, the transactions should reprocess successfully and proceed to Receipting Complete.