Solution : https://service.sap.com/sap/support/notes/169359 (SAP Service marketplace login required)
Key words :
reading internal table x_imonth1, symptom incorrect calculation, additional key words, 'internal error, time portions, monthly reference, termination occurs, error e9890, monthly basis, period procedure
Related Notes :
| 168983 | Collective note IS-T 1.2 - add-on patch 010 |