The OMVS command could not obtain TSO/E full-screen data from the terminal, because it was logged off.
The OMVS command ends and returns to TSO/E. Because the terminal is logged off, this error message will probably not show up on the screen.
For more information, see return code 20 from the TGET macro in z/OS TSO/E Programming Services.
If the terminal is logged off, log on to TSO/E, then reenter the OMVS command. If the terminal is not logged off, contact the system programmer.