---
title: "100 Continue — what it means and how to fix it"
description: "The server has read your request headers and wants you to send the body. What causes an HTTP 100, what to try as a visitor, and what to check if it is your own site."
url: https://atoneplace.net/error/100/
site: "At One Place"
---

# HTTP 100 — Continue

**HTTP 100: Continue**

The server has read your request headers and wants you to send the body.

## What 100 actually means

This is a handshake, not an error. A client with a large body to upload can send its headers first with an `Expect: 100-continue` header and wait, rather than pushing megabytes at a server that was going to reject the request anyway. A 100 is the server saying "headers look fine, go ahead". Browsers do not use this; it shows up in curl, in API clients, and in HTTP debugging traces.

## Common causes

- The client sent `Expect: 100-continue` before a large request body
- curl adds `Expect: 100-continue` automatically for bodies over 1 KB
- A proxy in the path is negotiating the upload on the client's behalf

## If you're just trying to view the page

1. Nothing — this never reaches you as a page, it is an intermediate step in a request
2. If you see it in a debugging tool, the request is proceeding normally

## If it's your site

1. If a server hangs on uploads, it may be ignoring `Expect: 100-continue`; send `-H "Expect:"` with curl to disable it
2. Nginx handles this automatically; older backends behind a proxy sometimes do not
3. Check that intermediaries are not stripping the `Expect` header before it reaches the origin

## Reference

- **Status code:** 100
- **Reason phrase:** Continue
- **Category:** 1xx — Informational
- **Defined in:** RFC 9110 §15.2.1

## Common questions

### What does HTTP 100 mean?

The server has read your request headers and wants you to send the body. This is a handshake, not an error. A client with a large body to upload can send its headers first with an `Expect: 100-continue` header and wait, rather than pushing megabytes at a server that was going to reject the request anyway.

### How do I fix a 100 error?

Nothing — this never reaches you as a page, it is an intermediate step in a request

### Is 100 a client error or a server error?

100 is in the 1xx range, which means informational. It is not an error at all.

## Related pages

- [101 Switching Protocols](https://atoneplace.net/error/101/)
- [103 Early Hints](https://atoneplace.net/error/103/)
- [102 Processing](https://atoneplace.net/error/102/)
- [104 Upload Resumption Supported](https://atoneplace.net/error/104/)

## Sources

- Hypertext Transfer Protocol (HTTP) Status Code Registry — IANA (https://www.iana.org/assignments/http-status-codes/)
- RFC 9110: HTTP Semantics — IETF (https://www.rfc-editor.org/rfc/rfc9110.html)