When you save an invoice after a credit memo is applied, the error message One or more accounts must be created to apply the credit memo may appear.
We are currently evaluating this issue and will update this article when we have more information.
Steps to Duplicate
1. Go to the vendor record having the issues 2. Go to The Activity tab 3. Look at the invoice 4. go to the payments and credits tab, apply the credit memo and then save the invoice, note that the error pops up