All error codes

metrics_unavailable

HTTP 503 Server metrics are temporarily unavailable

What happened

The metrics source did not answer for this server, or it answered with something that is not a series. You get an error rather than an empty series, because an empty series would state that there was no load.

What to do

Retry in a few seconds with the same parameters.

Retrying

The request itself is fine. Repeat it later; after a 5xx use a new idempotency key and read the resource first.

How it arrives

{
    "type": "https://docs.fiberax.com/errors/metrics_unavailable",
    "title": "Server metrics are temporarily unavailable",
    "status": 503,
    "code": "metrics_unavailable",
    "request_id": "a277dcd1ca652c65"
}

Branch your code on code, never on the wording of title.