HTTP 100 Continue — What It Means & How to Fix It

The HTTP 100 Continue status code means the server has received the initial part of the request and the client should continue sending the rest of the request body. This guide covers everything you need to know about this topic, including common causes, step-by-step solutions, and answers to frequently asked questions.

Here are the key things to understand: The 100 Continue status is an interim response indicating the initial request has been received.. It is commonly used when a client sends a large request body and wants confirmation before transmitting all data.. The client must send the Expect: 100-continue header to trigger this response.. If the server rejects the request, it responds with a final status code instead of 100.. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: Client sends Expect: 100-continue header before uploading a large payload.. Server acknowledges it is ready to accept the full request body.. Proxy servers forwarding the Expect header from the original client.. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Verify your client is correctly handling the 100 Continue interim response before sending the body.. Ensure the server is configured to support the Expect header.. If uploads stall, check timeout settings on both client and server.. Review proxy configurations that might strip the Expect header.. If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

This article is part of our HTTP Status Codes collection on Error Codes Wiki. We provide comprehensive, up-to-date information to help you find solutions quickly.