Rule Definition
The ON CHANGE OF statement can prove dangerous and is often misunderstood. Also, troubleshooting problems created by inadequate use of ON CHANGE OF statement can often be time-consuming because such errors are very difficult to reproduce and often appear to be random ones. Indeed, the use of the ON CHANGE OF statement is not suitable within functions or subroutines as many developers expect the comparison field's value to be reset for every new function call which is not the case. The control structure ON CHANGE OF - ENDON is not allowed in ABAP Objects, i.e. in a method.

Remediation
You can replace the ON CHANGE OF statements by explicitly programming the comparisons with IF statements.

Violation Code Sample

LOOP AT ts_invoices INTO wa_invoices
  ON CHANGE OF wa_invoices-matnr.
...
  ENDON.
ENDLOOP.

Fixed Code Sample

Remediation example:

LOOP AT ts_invoices INTO wa_invoices
  IF wa_invoices-matnr NE ltp_matnr_old.
    Ltp_matnr_old = wa_invoices-matnr.
...
  ENDIF.
ENDLOOP.

Enhancing the Quality of ABAP Development, Meijs-Krouwels-Heulmans-Sommen, SAP Press Page 98