2462664 - Transaction RZ70: Error "TP_REG_ACCESS_DENIED (thRc=748)" when opening an RFC connection

When running transaction RZ70 SLD registration, it fails with a message similar to:

0: SAPXXX01_XXX_00 : Used RFC destination: SLD_UC
0: SAPXXX01_XXX_00 : RFC call failed: Error when opening an RFC connection (CPIC-CALL: 'ThSAPOCMINIT', communication r

Right after the error, while checking the latest dev_rfcXX file from the work directory and search for an entry like:

======> CPIC-CALL: 'ThSAPOCMINIT', communication rc: CM_PARAMETER_ERROR (cmRc=19), taskhandler rc: TP_REG_ACCESS_DENIED (thRc=748)
Internal error, session terminated
ABAP Programm: RSLDAGDS (Transaction: RZ70)
User: SAPDIAG (Client: 100)
Destination: SLD_UC (Handle: 1, DtConId: 071129E79F2BF1A781170050568C198A, DtConCnt: 0, ConvId: ,)
EPP RootContextId: 0050568C198A1ED78AA21F4D29022117, ConnectionId: 00000000000000000000000000000000, ConnectionCnt: 0
EPP TransactionId: 071129E79F2BF16D81170050568C198A
Error RFCIO_ERROR_SYSERROR in /depot/bas/745_REL/src/krn/rfc/abrfcpic.c : 1835
CPIC-CALL: 'ThSAPOCMINIT', communication rc: CM_PARAMETER_ERROR (cmRc=19), taskhandler rc: TP_REG_ACCESS_DENIED (thRc=748)
Internal error, session terminated
DEST =SLD_UC
HOST =%%RFCSERVER%%
PROG =SLD_UC
GWHOST =hostname
GWSERV =sapgw00

• SAP Netweaver Release Independent.

RC=748, 748, SLD_UC, SLD_NUC, SLD RZ70, RZ70, gatewayHost, gatewayservice, service, host, connection test, SLD Servers , KBA , BC-CCM-SLD-ABA , System Landscape Directory ABAP Connectivity , BC-CST-GW , Gateway/CPIC , Problem