Internal main transaction & could not be found

What causes this issue?

Internal main transactions are used for internally determining the main
transaction in a document item.
All internal main transactions used can be found in system table
TFKIHVOR (internal transactions). Actual transactions are allocated to
internal transactions via table TFKIVV (allocation of internal
transactions to transactions).
The internal transaction used here
could not be determined from system table TFKIHVOR
has no allocation in table TFKIVV

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?

Error message extract from SAP system. Copyright SAP SE.