Message Oracle PGA-20949 - unable to define variable string for transaction recovery

ERRORunable to define variable string for transaction recovery
CAUSEThe gateway server was unable to define variable to be used in accessing the transaction log table during recovery processing. An Oracle server message will follow this message.
ACTIONEnsure that the Oracle server and its TNS listener are both operational. Also check the PGA_LOG_DB, PGA_LOG_USER, and PGA_LOG_PASS parameters in the gateway init file and ensure that they specify the correct database string, userid, and password, respectively. Refer to the Oracle Server Messages and Codes Manual for information on the Oracle server message.