Server error

504 504 Gateway Timeout

A proxy waited for the application and gave up. Something behind the front end is taking longer than the timeout allows.

Common causes

A slow database query or a missing index.
An external API call inside the request that is hanging.
A long-running import or report generated inside a web request.

How to fix it

Find the slow query — the slow query log will name it.
Move long jobs to a background worker and poll for the result.
Raise the timeout only as a stopgap; it hides the problem rather than fixing it.

See what a site actually returns

Run a live check and read the real status code, headers and timings.

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Other status codes

200 OK 201 Created 204 No Content 206 Partial Content 301 Moved Permanently 302 Found 303 See Other 304 Not Modified 307 Temporary Redirect 308 Permanent Redirect 400 Bad Request 401 Unauthorized 403 Forbidden 404 Not Found 405 Method Not Allowed 408 Request Timeout 410 Gone 413 Payload Too Large 418 I'm a Teapot 429 Too Many Requests 451 Unavailable For Legal Reasons 500 Internal Server Error 501 Not Implemented 502 Bad Gateway 503 Service Unavailable 507 Insufficient Storage 508 Loop Detected 521 Web Server Is Down 522 Connection Timed Out 523 Origin Is Unreachable 525 SSL Handshake Failed