Error message You cannot process a sales document with order type DMR1 (PBS) is displayed when you are trying to change Debit MemReq Service (DMR1) through Change Debit Memo Request app.
SAP S/4HANA CLOUD.
Sales Document DMR1 is of document type 'P' Project-Based Services (PBS) and cannot be changed or created using the standard Sales Order App.
For project related debit memo request, you need to use Edit Billing Request app.
Message no. V2455, V2455, Edit Billing Request, service, PBS, DMR1, debit memo request , KBA , SD-BIL-IV-SM , Resource-Related Billing , SD-SLS , Sales , How To