Symptoms
Sales Order that includes a domain transfer fails with the error
Configuration #0 does not exist
The domain getting transferred has External DNS hosting type currently.
Cause
The domain already existed in the system before or experienced incomplete provisioning and was changed to external DNS hosting. In such conditions, an attempt to transfer the domain fails.
Resolution
Go to PCP > Domains > your domain and switch it to internal DNS hosting. Resubmit the SO for provisioning after that.