Unable to enter Vendor Credits: Notice: SuiteScript Error. Invalid account reference key XX

The error message means that the account used for the vendor credits having an Internal ID:XX is marked inactive.

To verify:

1. Navigate to Lists > Accounting > Accounts

2. Check the Show Inactives box located at the footer

3. Look for the account with the Internal ID of XX.

Note: Either uncheck the Inactive box of the account or assign an active account.