HTTP/1xx (Informational)
103 Early Hints
Lets the server send preload Link headers before the final response so the browser can start fetching critical assets early.
❓ Why does this happen?
CDNs such as Cloudflare and Fastly emit 103 Early Hints to speed up Largest Contentful Paint (LCP).
✅ How to fix it
Expected performance optimization. Make sure the final response repeats the same Link headers for clients that ignore 103.
Return or handle 103 in your stack
// Route Handlers cannot return 1xx responses: the Response constructor
// only accepts status codes 200-599. 103 Early Hints is emitted by the server/CDN layer.Live 103 mock endpoint
103 is an interim 1xx response. Browsers and the Fetch API never expose 1xx codes as a final response, so it cannot be mocked directly. Try /api/mock/200 instead.
Frequently Asked Questions
What does HTTP Status 103 mean?
Why am I getting a 103 status code?
How do I fix a 103 Early Hints error?
Other 1xx status codes
Browse the full HTTP status codes directory or troubleshoot terminal errors in the Error Fix Encyclopedia.