Not all rows in PRCD_ELEMENTS were processed. See long text.

What causes this issue?

Following an SAP S/4HANA migration, program PRC_MIG_POST_PROCESSING was
executed. After execution, the warning "Not all rows in PRCD_ELEMENTS
were processed. See long text." is displayed. In addition, following the
execution of PRC_MIG_POST_PROCESSING, you might have verified table
PRCD_ELEMENTS and noticed that some records have an unusual value of '2'
in field WAERK.
Note that having a value of '2' in the WAERK field in itself is not a
serious issue. It means that the row assumes a currency type with 2
digits after the decimal place, exactly as classical SAP ERP did. The
monetary amount contained in field KAWRT (and shown in the user
interface) remains correct.

System Response

Some rows in table PRCD_ELEMENTS have a value of '2' in field WAERK

How to fix this error?

Let us use the term "surplus records" for any records that remain in
table PRCD_ELEMENTS with field WAERK having a value of '2' after
executing PRC_MIG_POST_PROCESSING.
Follow these troubleshooting instructions:
Step 1: Look at the surplus records.
Step 2: Are these test records that were manually inserted into table
KONV?
?,,If the surplus records are test records, they can be ignored. You
have completed the troubleshooting.
?,,If not, see SAP Note 2353115 for more information.

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.