The HTTP100 Continueinformational 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 anExpect: 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 followingPUT 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 like405,401, or403.At first, the client sends headers only, including anExpect: 100-continue header:

PUT /videos HTTP/1.1Host: uploads.example.comContent-Type: video/h264Content-Length: 123456789Expect: 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

See also

• Expect
• 417