Bug ID 658382: Large numbers of ERR_UNKNOWN appearing in the logs

Last Modified: Sep 13, 2023

Affected Product(s):
BIG-IP LTM(all modules)

Known Affected Versions:
12.1.2, 12.1.3,,,,,,,, 12.1.4, 13.1.0,,,,,,,,, 13.1.1,,,, 14.0.0,,,,,, 14.0.1,

Fixed In:

Opened: Apr 13, 2017

Severity: 5-Cosmetic


There are times when LTM Policy subsystem attempts to execute particular actions, which fail and result in LTM Policy writing an error to the logs with an error type of ERR_UNKNOWN.


This is a case of unnecessary logging, and there is no adverse effect other than a higher-than-normal amount of logging.


This has been observed when plugins are active and experiencing high traffic volumes. The logging of ERR_UNKNOWN occurs when filters and plug-ins experience failures (such as out of memory) and react by initiating a reset of the connection. When these filters and plug-ins return an error to LTM Policy, LTM Policy logs ERR_UNKNOWN.



Fix Information


Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips