HTTP 100 Continue vs 510 Not Extended
HTTP 100 (Continue) is a 1xx Informational response, while 510 (Not Extended) is a 5xx Server 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, 510 means that further extensions to the request are required for the server to fulfill it.
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
Further extensions to the request are required for the server to fulfill it.
When You See It
When an HTTP extension required by the server is not present in the request.
How to Fix
Add the required extension headers to your request.
Key Differences
100 is a 1xx Informational response, while 510 is a 5xx Server 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 510: Further extensions to the request are required for the server to fulfill it.
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 510 when when an HTTP extension required by the server is not present in the request.
When to Use Which
For 100 (Continue): This is an interim response — no fix needed. The client should continue sending the request body. For 510 (Not Extended): Add the required extension headers to your request.