My Oracle Support Banner

Versions 11, 12 and Newer Databases: Fatal NI Connect Error 12170, 'TNS-12535: TNS:operation timed out' Reported in Alert Log (Doc ID 1286376.1)

Last updated on DECEMBER 30, 2022

Applies to:

Oracle Net Services - Version to [Release 11.1 to 12.2]
Oracle Database - Enterprise Edition - Version to [Release 19]
Information in this document applies to any platform.
TNS-12170, ORA-12170, TNS-12535, TNS-00505 alert.log


nt secondary err code: 110   Monitoring of the 11g database Alert log(s) may show frequent timeout related messages such as:

- On Oracle Solaris:


Fatal NI connect error 12170.

TNS for Solaris: Version - Production
Oracle Bequeath NT Protocol Adapter for Solaris: Version - Production
TCP/IP NT Protocol Adapter for Solaris: Version - Production
Time: 22-JAN-2011 21:48:23
Tracing not turned on.
Tns error struct:
ns main err code: 12535

TNS-12535: TNS:operation timed out
ns secondary err code: 12560
nt main err code: 505

TNS-00505: Operation timed out
nt secondary err code: 145
nt OS err code: 0
Client address: (ADDRESS=(PROTOCOL=tcp)(

The "nt secondary err code" will be different based on the operating system.

Linux x86 or Linux x86-64: "nt secondary err code: 110"
HP-UX Server: "nt secondary err code: 238"
AIX: "nt secondary err code: 78"


No changes are necessary, but may have recently upgraded the database to 11g release 1 or higher, or installed a new Oracle11g database.

Note: Prior to 11gR1 these same 'Fatal NI connect error 12170' are written to the sqlnet.log


To view full details, sign in with your My Oracle Support account.

Don't have a My Oracle Support account? Click to get started!

In this Document

My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts.