2757680 - ME59N inconsistent error messages for the same Purchase Requisition

When using ME59N, you notice the following anomalies:

• If a PR is assigned with only the purchasing organization (fixed vendor is missing), ME59N provides error "Different source maintained for requisition". This does not make any sense.
• If the same PR undergoes the same run, by itself, the system correctly identifies the error and provides error "Enter a vendor".

You'd like to know why this is, especially for planning a custom enhancement (for example, automated PO creation via BAPI).

Read more...

• Materials Management (MM)
• SAP ERP Central Component
• SAP ERP
• SAP enhancement package for SAP ERP

SAP ERP 6.0 ; SAP ERP Central Component 6.0 ; SAP R/3 2.2E ; SAP R/3 2.2F ; SAP R/3 2.2G ; SAP R/3 2.2H ; SAP R/3 2.2I ; SAP R/3 2.2J ; SAP R/3 3.0A ; SAP R/3 3.0B ; SAP R/3 3.0C ; SAP R/3 3.0D ; SAP R/3 3.0E ; SAP R/3 3.0F ; SAP R/3 3.1G ; SAP R/3 3.1H ; SAP R/3 3.1I ; SAP R/3 4.0A ; SAP R/3 4.0B ; SAP R/3 4.5A ; SAP R/3 4.5B ; SAP R/3 4.6A ; SAP R/3 4.6B ; SAP R/3 4.6C ; SAP S/4HANA 1610 ; SAP S/4HANA 1709 ; SAP S/4HANA 1809 ; SAP S/4HANA, on-premise edition 1511 ; SAP enhancement package 1 for SAP ERP 6.0 ; SAP enhancement package 2 for SAP ERP 6.0 ; SAP enhancement package 3 for SAP ERP 6.0 ; SAP enhancement package 4 for SAP ERP 6.0 ; SAP enhancement package 4 for SAP ERP 6.0 on SAP enhancement package for SAP NetWeaver 7.0 ; SAP enhancement package 5 for SAP ERP 6.0 ; SAP enhancement package 6 for SAP ERP 6.0 ; SAP enhancement package 7 for SAP ERP 6.0 ; SAP enhancement package 8 for SAP ERP 6.0 ; SAP enhancement package for SAP ERP 2005

EBAN-ZUGBA , fixed source of supply , desired vendor , Wunschlieferant , fester Lieferant , Bezugsquelle , RM06BB20 , RM06BB30 , ME261 , ME 261 , No suitable purchase requisitions found , Es wurden keine passenden Bestellanforderungen gefunden, bestellanforderung, banf , zugeordnet, bezugsquelle , fester lieferant , fixed vendor supplier , ME_REQUISITION_SET_ZUGBA , KBA , MM-PUR-PO , Purchase Orders , MM-PUR-PO-GUI , Userinterface - Purchase Orders , MM-PUR-SQ , Sources of Supply , Problem