Component &1: Operation not found in order &2

What causes this issue?

In order &V2&, the component or item with material number &V1& was added
in an external system. This should now be implemented in the order in
SAP ECC. For this, it was set that the new component should be assigned
to the operation with the internal key (APLZL) &V3&. However, an
operation with this internal key does not exist in SAP ECC for order
&V2&.

System Response

The processing of order &V2& is terminated.

How to fix this error?

Check the data that was transferred from the external system to SAP ECC
or check the data in the external system.

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.