Oracle Message ORA-12535 - TNS: operation timed out

ERRORTNS: operation timed out
CAUSEThe requested operation could not be completed within the time out period.
ACTIONLook at the documentation on the secondary errors for possible remedy. See SQLNET.LOG to find secondary error if not provided explicitly. Turn on tracing to gather more information.

381105ORA-12203 / ORA-12535 when starting the R/3 work processes
131561Work processes sometimes abend during database connect
34479Collective note for problems with SQL-Net V2 ORACLE