Oracle Database / Connections & Oracle Net
ORA-12545: check host names embedded in Oracle connect descriptors
A connection can fail because the configured target cannot be resolved or reached, including a redirected target name. Inspect every host in the effective descriptor.
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 resolved descriptor can expose the host and port selected by the naming method. A multi-address descriptor may contain names that work only from certain networks.
Resolve and verify
Compare those names with approved DNS from the affected application host. Correct invalid addresses or network-specific service configuration, then retest all intended endpoints.
Operational precautions
Do not hard-code an arbitrary IP address in place of a managed cluster name. It can bypass failover design and break later maintenance.