2410118 - CTS_WBO_GET_DEFAULT_REQUEST fails with INVALID_USER JCo Exception

Choose CTS+ from the dropdown in System Management -> Configurations menu of MII. The error like the one below is written to the traces:

Error executing function (check stacktrace for details): CTS_WBO_GET_DEFAULT_REQUEST [EXECUTION_ERROR_CHECK_STACKTRACE]
[EXCEPTION]
com.sap.conn.jco.JCoException: (126) INVALID_USER(EXISTENCE..): User ADMINISTRATO does not exist in the system (or locked).
at com.sap.tc.ts.cts.impl.adapters.jco.JCoAdapter.getException(JCoAdapter.java:188)
at com.sap.tc.ts.cts.impl.adapters.jco.JCoAdapter.executeFunction(JCoAdapter.java:162)
at com.sap.tc.ts.cts.impl.adapters.jco.TmsJCoAdapterNew.getMyDefaultRequest(TmsJCoAdapterNew.java:353)
at com.sap.tc.ts.cts.impl.adapters.jco.TmsTransportConfig.getMyDefaultRequestId(TmsTransportConfig.java:61)
at com.sap.tc.ts.es.impl.ExportManagerImpl.getMyDefaultRequest(ExportManagerImpl.java:90)
at com.sap.tc.ts.es.impl.ExportManagerImpl.getMyDefaultRequest(ExportManagerImpl.java:77)
at com.sap.xmii.system.BackupManager.getTransportRequest(BackupManager.java:1683)
at com.sap.xmii.ejb.sysadmin.BackupRestoreBean.getTrasportRequest(BackupRestoreBean.java:56)...

SAP Manufacturing Integration and Intelligence

KBA , MFG-MII , SAP Manufacturing Integration and Intelligence , BC-CTS-TMS-PLS , TMS for non-ABAP (CTS+) , Problem