Bug ID 450030: Vary header always generated for browser-specific content

Last Modified: Nov 07, 2022

Bug Tracker

Affected Product:  See more info
BIG-IP WAM(all modules)

Known Affected Versions:
11.5.0, 11.5.1, 11.5.1 HF1, 11.5.1 HF10, 11.5.1 HF11, 11.5.1 HF2, 11.5.1 HF3, 11.5.1 HF4

Fixed In:
11.6.0, 11.5.1 HF5

Opened: Feb 24, 2014
Severity: 4-Minor


When WA optimized images to WebP format, the first WebP response for each image is served without a Vary header. The header is present for subsequent responses where the WebP is served from cache.


Omitting the Vary header might allow downstream caches to incorrectly cache and serve WebP content to browsers which do not understand it.


Both Image-optimization and Optimize-for-client enabled in the WA Policy and requests for images from WebP capable browsers behind downstream caches.



Fix Information

The Vary on user-agent header is properly generated whenever WebP content is served.

Behavior Change