HTTP 100 Continue vs 504 Gateway Timeout
HTTP 100 (Continue) is a 1xx Informational response, while 504 (Gateway Timeout) 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, 504 means that the server, acting as a gateway or proxy, did not receive a timely response from the upstream server.
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, acting as a gateway or proxy, did not receive a timely response from the upstream server.
When You See It
When an upstream server is too slow to respond within the proxy's timeout window.
How to Fix
Increase proxy timeout settings. Optimize upstream server performance. Check for long-running queries.
Key Differences
100 is a 1xx Informational response, while 504 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 504: The server, acting as a gateway or proxy, did not receive a timely response from the upstream server.
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 504 when when an upstream server is too slow to respond within the proxy's timeout window.
When to Use Which
For 100 (Continue): This is an interim response — no fix needed. The client should continue sending the request body. For 504 (Gateway Timeout): Increase proxy timeout settings. Optimize upstream server performance. Check for long-running queries.