Critical severityconnectivity
Oracle Database Error:
ORA-12543
What does this error mean?
The TNS connection attempt failed because the target Oracle host is not reachable on the network.
Common causes
- 1Oracle server is down or rebooting
- 2Network route between pipeline server and Oracle host is unavailable
- 3Firewall or security group blocks all traffic to the Oracle host
- 4Wrong host name or IP address in the connection string
- 5Oracle host is in a different VNet/VPC with no peering or private endpoint configured
How to fix it
- 1Step 1: Ping the Oracle host from the pipeline server: `ping <oracle_host>`.
- 2Step 2: Test TCP connectivity: `telnet <oracle_host> 1521` or `nc -zv <oracle_host> 1521`.
- 3Step 3: Verify the host name/IP in the connection string resolves correctly: `nslookup <oracle_host>`.
- 4Step 4: Check network security groups and firewall rules.
- 5Step 5: For Azure/cloud environments, verify VNet peering, private endpoints, or service endpoints are configured.
Example log output
ORA-12543: TNS:destination host unreachable