Config:
W3TC config is set to ONLY enable Disk:Basic Page Caching and “Browser Caching” to add expires headers. No other features are enabled.
Plugins:
We have no Gzip plugins enabled. After searching, I do see plugins that call ob_start():
* WordPress SEO uses ob_start() so it can replace the <title> tag
* Page Navi uses ob_start() to capture <link>’s
* Our custom theme uses ob_start() twice to capture and replace WordPress content.
We do use gzip compression but not in PHP; we let our CDN handle last-mile acceleration for us.
This issue occurs once a day (~1 in 50k-70k WordPress requests). So I suspect it’s related to a rare race condition involving temp/cache files or headers. I just don’t have enough experience with this plugin to isolate it.
