Some entries in client &1 could not be converted

What causes this issue?

Transaction exist in <LB>TEIVV</> that are no longer defined in
<LB>TFKHVO</> or in <LB>TFKTVO</>.

System Response

The corresponding entries in <LB>TEIVV</> were not converted. For
safety's sake, old entries for successfully converted entries also
remain in <LB>TEIVV</>. They are deleted only once the report has
converted all entries in all clients.

How to fix this error?

Having made additional entries to table <LB>TFKHVO</>, and/or
<LB>TFKTVO</>, you will need to restart the report.

Error message extract from SAP system. Copyright SAP SE.