Material &: No operations exist - planned order conversion terminated

What causes this issue?

No routing or operations could be found for material &V1&. Since in
Customizing for the order type it is specified that the order can only
be generated from a routing, planned order conversion is terminated.

System Response

Planned order conversion is terminated.

How to fix this error?

Either change the setting for the order type or create a routing for
the material.

Error message extract from SAP system. Copyright SAP SE.