HTTP 100 Continue vs 203 Non-Authoritative Information
HTTP 100 (Continue) is a 1xx Informational response, while 203 (Non-Authoritative Information) is a 2xx Success 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, 203 means that the response payload has been modified by a transforming proxy from the origin server's 200 response.
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 response payload has been modified by a transforming proxy from the origin server's 200 response.
When You See It
When a proxy or CDN modifies the response body (e.g., adds headers, transforms content).
How to Fix
Check if a proxy is modifying the response. Access the origin directly if you need the original content.
Key Differences
100 is a 1xx Informational response, while 203 is a 2xx Success 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 203: The response payload has been modified by a transforming proxy from the origin server's 200 response.
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 203 when when a proxy or CDN modifies the response body (e.g., adds headers, transforms content).
When to Use Which
For 100 (Continue): This is an interim response — no fix needed. The client should continue sending the request body. For 203 (Non-Authoritative Information): Check if a proxy is modifying the response. Access the origin directly if you need the original content.