Business partner GUID &1 does not exist

What causes this issue?

The business partner GUID &1 does not exist in table BUT000.

System Response

An entry cannot be created for a non-existent partner.

How to fix this error?

Check your business partner GUID and the business partner table BUT000.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.