ORA-03113 Connection Drops After Inactivity on Oracle CMAN Setup
Description:
We are experiencing intermittent disconnections on our Oracle 19c Single-Instance HA database when clients connect via JDBC Thin. All connections are routed through a single Connection Manager (CMAN). No firewall exists between the application and database servers.
Environment:
- Database: Oracle SE HA (1 active node)
- Client: Oracle Instant Client 19.27 (Basic Lite)
- Driver: Oracle JDBC Driver,
ojdbc8.jar, Version 19.27.0.0.0 - Connection type: JDBC Thin
- SQL*Plus: Not yet tested from application server
- Network: No firewall between client and DB
Issue Details:
- Symptom: Established connections intermittently disconnect
- Timestamp example:
16:14:04.773 23/09/2025
Configuration Files :
Server DB Node 1 (DB-Node-1):
# SQLNET.ORA for DB-Node-1 NAMES.DIRECTORY_PATH= (TNSNAMES, EZCONNECT) SQLNET.EXPIRE_TIME=10 SQLNET.SEND_TIMEOUT=240 DISABLE_OOB=on TCP.NODELAY=YES SQLNET.ALLOWED_LOGON_VERSION_CLIENT=11
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