100 Continue
The HTTP 100 Continue informational response status code indicates that the initial part of a request has been received and has not yet been rejected by the server.
The client should continue with a request or discard the 100 response if the request is already finished.
When a request has an Expect: 100-continue header, the 100 Continue response indicates that the server is ready or capable of receiving the request content.
Waiting for a 100 Continue response can be helpful if a client anticipates that an error is likely, for example, when sending state-changing operations without previously verified authentication credentials.
Status
100 Continue
Examples
PUT request with 100 Continue
The following PUT request sends information to a server about a file upload.
The client is indicating that it will proceed with the content if it receives a 100 response to avoid sending data over the network that could result in an error like 405, 401, or 403.
At first, the client sends headers only, including an Expect: 100-continue header:
PUT /videos HTTP/1.1
Host: uploads.example.com
Content-Type: video/h264
Content-Length: 123456789
Expect: 100-continue
The server indicates that the request can proceed:
HTTP/1.1 100 Continue
The client completes the request by sending the actual data:
[Video data as content for PUT request]
Specifications
| Specification |
|---|
| HTTP Semantics # status.100 |