Symptom

Unknown command has been specified within the URL.

Solution

Very specifically if this exception is raised on the startup URL (as used by NWBC for Desktop) of /sap/bc/nwbc/TicketIssuer, it is a clear indicator that the ABAP system has only a beta version of the NWBC runtime that is not officially supported.

See INSTALL.03 On which SAP NetWeaver Versions is NWBC v3.0 supported? and update the service pack level to a minimum level supported.