HTTP 100 Continue vs 505 HTTP Version Not Supported
HTTP 100 (Continue) is a 1xx Informational response, while 505 (HTTP Version Not Supported) 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, 505 means that the server does not support the HTTP version used in the request.
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 does not support the HTTP version used in the request.
When You See It
When a client uses an HTTP version the server doesn't support.
How to Fix
Use a supported HTTP version (typically HTTP/1.1 or HTTP/2).
Key Differences
100 is a 1xx Informational response, while 505 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 505: The server does not support the HTTP version used in the request.
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 505 when when a client uses an HTTP version the server doesn't support.
When to Use Which
For 100 (Continue): This is an interim response — no fix needed. The client should continue sending the request body. For 505 (HTTP Version Not Supported): Use a supported HTTP version (typically HTTP/1.1 or HTTP/2).