5xx · Server errorretryable

504Gateway Timeout

The server was acting as a gateway or proxy and did not receive a timely response from the upstream server.

What this code obliges you to do

Retry

Safe to retry

Repeating the same request can succeed, so a client may back off and try again. Honour Retry-After when the response sends one.

Caching

Not cacheable by default

Caches will not store this response unless you send explicit freshness headers saying they may.

Response body

Body allowed

You may return a payload explaining the outcome — for an error, a machine-readable problem document is worth the effort.

Long-running database query blocking worker threads

Upstream 3rd party API freezing

Negative. Indicates application is far too slow, significantly harming Crawl Budgets.

AWS

// Typically seen in AWS API Gateway when Lambda exceeds 30s timeout

The server timed out waiting for the request. The client did not produce a request within the time that the server was prepared to wait.

The server was acting as a gateway or proxy and received an invalid response from the upstream server.

Class5xx

RetrySafe

CacheNo

BodyAllowed