Registration type &1 has no milestones assigned

What causes this issue?

For registration projects, every registration type must have at least
one milestone. However, registration type &V1& has no milestone
assigned.

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?

In the Customizing activity <LS>Define Project Milestones for
Registration Projects</>, define at least one milestone for every
registration type.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.