This is due to the payment batch limit in Twinfield. If you shorten the length of the supplier name, you should be able to add the supplier. Twinfield has a limit of 40 characters in the supplier name.
Twinfield: Supplier creation failure. Beneficiary is invalid.
When creating/saving a supplier, I get this message. What does this error message mean?

Written by Patrick Blijs
Updated this week