HTTP 417 Expectation Failed vs 502 Bad Gateway
HTTP 417 (Expectation Failed) is a 4xx Client Error response, while 502 (Bad Gateway) is a 5xx Server Error response. 417 indicates that the server cannot meet the requirements of the Expect header. In contrast, 502 means that the server, acting as a gateway or proxy, received an invalid response from the upstream server.
Description
The server cannot meet the requirements of the Expect header.
When You See It
When the server doesn't support Expect: 100-continue.
How to Fix
Remove the Expect header from your request.
Description
The server, acting as a gateway or proxy, received an invalid response from the upstream server.
When You See It
When Nginx/Apache can't reach the application server (e.g., Gunicorn is down, upstream timeout).
How to Fix
Check if the upstream server is running. Verify proxy configuration. Check for upstream timeouts.
Key Differences
417 is a 4xx Client Error response, while 502 is a 5xx Server Error response.
HTTP 417: The server cannot meet the requirements of the Expect header.
HTTP 502: The server, acting as a gateway or proxy, received an invalid response from the upstream server.
You encounter 417 when when the server doesn't support Expect: 100-continue.
You encounter 502 when when Nginx/Apache can't reach the application server (e.g., Gunicorn is down, upstream timeout).
When to Use Which
For 417 (Expectation Failed): Remove the Expect header from your request. For 502 (Bad Gateway): Check if the upstream server is running. Verify proxy configuration. Check for upstream timeouts.