First execute planning run (multi-level) for material &1

What causes this issue?

The planned order cannot be converted as the related order network is
not complete. This affects component &V2&. A planned order was not
created for the secondary requirement of the components manufactured
directly.
This can be done by multi-level material requirements planning.

System Response

How to fix this error?

Start multi-level material requirements planning for the planned order
material.
If conversion is still not possible after you have carried out
multi-level planning, investigate the following:
Was the order network planned successfully, or did the program
terminate during planning? Check the termination MRP lists.
Check whether the material master for the directly manufactured
assemblies is maintained correctly. The MRP type should be set so that
that material is planned (that means it should not be set to 'ND').
Dependent requirements should be relevant for planning.
Is there is a fixed planned order for an assembly in the order network
for which the order quantity differs from the quantity of the
initiating secondary requirement? If so, deselect the flag for fixing
the planned order, or adjust the quantity and then carry out planning
again.

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.