HTTP Status Code

100 Continue

Informational

The server received the request headers and the client should continue sending the request body.

HTTP status code reference, response example, common causes, fixes, and related status codes.

What does HTTP 100 Continue mean?

HTTP 100 Continue is a status code sent by a server to indicate the result of an HTTP request.

Status codes help browsers, APIs, apps, and backend systems understand whether a request succeeded, failed, was redirected, or needs additional action.

In practice, HTTP 100 Continue usually appears when a server responds under specific request, validation, permission, or infrastructure conditions.

Response example

HTTP/1.1 100 Continue

HTTP example

HTTP/1.1 100 Continue

Relevant headers

Expect

Expect: 100-continue

Common causes

Large request body expected
Client sending request in multiple stages
Expect: 100-continue workflow

How to fix it

Usually handled automatically by the HTTP client
Check Expect headers if upload behavior seems unusual

Common mistakes

Assuming the status code alone explains the full backend issue
Ignoring related response headers that add important context
Treating temporary errors as permanent failures
Retrying too aggressively without checking the cause
Debugging the frontend only when the problem is server-side

How browsers and APIs use it

Browsers, APIs, and backend services use HTTP status codes to understand the outcome of a request. Depending on the status code, an application may render content, retry a request, redirect the user, show an error, or trigger a different flow in the client or server.

Developer note

You usually do not handle HTTP 100 manually in frontend code. It is mostly relevant for lower-level clients, uploads, and proxies.

Related status codes

HTTP 101