HTTP 100 Continue vs 411 Length Required
HTTP 100 (Continue) is a 1xx Informational response, while 411 (Length Required) is a 4xx Client Error response. 100 indicates that the server has received the request headers and the client should proceed to send the request body. This lets the client know it can continue with the request or abort if the headers were rejected. In contrast, 411 means that the server refuses to accept the request without a Content-Length header.
Description
The server has received the request headers and the client should proceed to send the request body. This lets the client know it can continue with the request or abort if the headers were rejected.
When You See It
When a client sends an Expect: 100-continue header, the server responds with 100 before the client sends the body.
How to Fix
This is an interim response — no fix needed. The client should continue sending the request body.
Description
The server refuses to accept the request without a Content-Length header.
When You See It
When sending a request body without specifying Content-Length.
How to Fix
Include a Content-Length header in your request.
Key Differences
100 is a 1xx Informational response, while 411 is a 4xx Client Error response.
HTTP 100: The server has received the request headers and the client should proceed to send the request body. This lets the client know it can continue with the request or abort if the headers were rejected.
HTTP 411: The server refuses to accept the request without a Content-Length header.
You encounter 100 when when a client sends an Expect: 100-continue header, the server responds with 100 before the client sends the body.
You encounter 411 when when sending a request body without specifying Content-Length.
When to Use Which
For 100 (Continue): This is an interim response — no fix needed. The client should continue sending the request body. For 411 (Length Required): Include a Content-Length header in your request.