The Cloudflare Caching Bug Breaking Inertia-Powered Websites

Developers using Inertia with Cloudflare face a critical caching vulnerability: the edge cache ignores Vary headers, serving cached HTML to AJAX requests expecting JSON, which silently breaks applications in production. This issue exposes a fundamental misunderstanding about cache defense mechanisms—store-time protections like no-store are ineffective when edge caches ignore the Vary header at lookup time. Proper configuration requires either disabling edge caching for Inertia responses or implementing Cloudflare Cache Rules to enforce correct cache behavior.