Partner does not have a customer role, you cannot create a customer

What causes this issue?

You can set the indicator 'CREATE_CUSTOMER' only if the business partner
has a valid optional customer role.

System Response

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

How to fix this error?

Set the indicator only for valid optional customer roles.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.