2994373 - "Subfield access (offset = 19, length = 0) to a data object of size 19 outside valid limits." error when using Web Services ABAP

On the provider (server) side the system raises the following error message in transaction SRT_UTIL.
Also, in the payload of the message there is no <DOCNUM></DOCNUM> field.

• ---TYPE: CX_SY_RANGE_OUT_OF_BOUNDS
• ---ERROR_TEXT: Subfield access (offset = 19, length = 0) to a data object of size 19 outside valid limits.

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• SAP to SFSF Org Structure Replication
• Middleware Integration (HCI or Dell Boomi)
• ABAP Web Services
• SAP NetWeaver
• SAP NetWeaver Application Server for SAP S/4HANA
• ABAP PLATFORM - Application Server ABAP

SAP ERP 6.0 ; SAP NetWeaver 2004 ; SAP NetWeaver 7.0 ; SAP NetWeaver 7.1 ; SAP NetWeaver 7.2 ; SAP NetWeaver 7.3 ; SAP NetWeaver 7.4 ; SAP NetWeaver 7.5 ; SAP enhancement package 1 for SAP NetWeaver 7.0 ; SAP enhancement package 1 for SAP NetWeaver 7.3 ; SAP enhancement package 2 for SAP NetWeaver 7.0 ; SAP enhancement package 3 for SAP NetWeaver 7.0

Subfield access (offset = 19, length = 0) to a data object of size 19 outside valid limits., Subfield access, outside valid limits, object of size 19, Web Services ABAP, ABAP, CX_SY_RANGE_OUT_OF_BOUNDS, DOCNUM, IDOC, SRT_UTIL , KBA , BC-ESI-WS-ABA , Web Service and SOAP - ABAP , BC-MID-ALE , Integration Technology ALE , Problem