Oracle Database / Connections & Oracle Net
ORA-12170: separate connection timeout stages
A timeout can occur during network establishment or later connection negotiation. Capture the client timestamp and endpoint before changing timeout values.
Environment and inputs: Oracle Database 19c baseline · SQL*Plus-compatible SQL unless RMAN, DGMGRL, ADRCI or a host shell is specified. Check release, patch level, edition and container first.
Start with this diagnostic
Use the stated SQL, RMAN, DGMGRL or host shell and replace sample names with approved targets. DBA and V$ views need authorized catalog access in the correct container. Do not grant broad privileges for an example.
tnsping APPDBRead the result
The client-side probe helps identify alias resolution and listener reachability. A prompt response still leaves authentication, service handlers and application driver behavior untested.
Resolve and verify
Compare listener and server logs at the same time, then inspect the network path and client timeout settings. Reproduce with a bounded real connection from the affected host.
Operational precautions
Increasing timeouts can hide a network or capacity fault. Do not infer a database outage from one timed-out probe.