command is only valid in multiprocess and/or kept debugger
 configuration

    Facility: DEBUG, VMS Debugger

    Explanation: The debugger was unable to execute the specified
    command because the current configuration of the debugger does
    not allow connection or disconnection. The specified command is
    only valid when the debugger's multiprocess support is enabled,
    or when the debugger is running in the "kept" configuration.

    User Action: Restart the debugging session with multiprocess
    support enabled in the kept debugger. Multiprocess support is
    enabled by defining the logical name DBG$PROCESS as follows: ($
    DEFINE/JOB DBG$PROCESS MULTIPROCESS) The kept debugger is usually
    invoked with the following command: $ RUN SYS$SHARE:DEBUGSHR
    Your system may be different; consult your release notes and your
    system management.