113 Heuristic Expiration
The HTTP 113 Heuristic Expiration warning code indicates a cache heuristically chose a freshness lifetime greater than 24 hours, and the chosen lifetime has expired. The code is attached to the Warning header in the HTTP response.
Note
The warning code 113 Heuristic Expiration and the Warning header have been obsoleted.
Example
Warning: 113 www.example.re "Heuristic Expiration"
See also
Last updated: April 4, 2026