HTTP 412 Precondition Failed vs 504 Gateway Timeout
HTTP 412 (Precondition Failed) is a 4xx Client Error response, while 504 (Gateway Timeout) is a 5xx Server Error response. 412 indicates that one or more conditions in the request headers (If-Match, If-Unmodified-Since) evaluated to false. In contrast, 504 means that the server, acting as a gateway or proxy, did not receive a timely response from the upstream server.
Description
One or more conditions in the request headers (If-Match, If-Unmodified-Since) evaluated to false.
When You See It
When using conditional requests with ETags and the resource has changed.
How to Fix
Refresh the ETag/Last-Modified value and retry with updated preconditions.
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
412 is a 4xx Client Error response, while 504 is a 5xx Server Error response.
HTTP 412: One or more conditions in the request headers (If-Match, If-Unmodified-Since) evaluated to false.
HTTP 504: The server, acting as a gateway or proxy, did not receive a timely response from the upstream server.
You encounter 412 when when using conditional requests with ETags and the resource has changed.
You encounter 504 when when an upstream server is too slow to respond within the proxy's timeout window.
When to Use Which
For 412 (Precondition Failed): Refresh the ETag/Last-Modified value and retry with updated preconditions. For 504 (Gateway Timeout): Increase proxy timeout settings. Optimize upstream server performance. Check for long-running queries.