If the error appears intermittently, you are likely hitting connection pool limits.
| Exception | Meaning | | :--- | :--- | | Login failed for user | Bad credentials | | Connection refused: connect | Port unreachable or DB not listening | | Invalid Oracle URL syntax | Wrong JDBC URL format | | IO Error: The network adapter could not establish the connection | Network issue or listener down | | ORA-28000: the account is locked | User account locked in Oracle | | SSLHandshakeException | Certificate or TLS mismatch | If the error appears intermittently, you are likely