Errors

Every error from /v1 has the same shape:

{
  "error": {
    "code": "invalid_parameter",
    "message": "stat: is not a parameter of this endpoint",
    "param": "stat"
  }
}

code is stable, and is what your program should switch on. It will not change within /v1.
message is a sentence for a person. It may be reworded at any time; do not parse it.
param names the query parameter at fault, on invalid_parameter only.

Every response, error or not, also carries an x-request-id header. Quote it if you write to us about a call.

The codes

Status	`code`	What happened	What to do
`400`	`invalid_parameter`	A parameter is unknown, malformed or out of range, or a cursor is not one this API issued. `param` names it.	Fix the request. Retrying it unchanged will fail the same way.
`401`	`unauthorized`	No key, a key that is not valid or has been revoked, or a key sent in the URL.	Send a valid key in the `Authorization` header. See Authentication.
`402`	`payment_required`	The key's account has no API plan, its plan's first payment is still being confirmed, or billing is past due. The message says which.	Start the plan in Settings › API, wait a few seconds for its payment, or update the card in Settings › Billing.
`403`	`forbidden`	The key's account is suspended, or its API access is switched off.	Contact us.
`404`	`not_found`	No outage or network has that id, or the path is not an endpoint.	Check the id. Outage ids are stable for an outage's whole life.
`429`	`rate_limited`	The key is over its per-minute limit, or this address has had 20 requests refused for a missing or bad key in the last minute.	Wait for the `retry-after` header's seconds; for the second, fix the key first. See Rate limits.
`500`	`internal_error`	Something failed on our side. It has been logged.	Retry with a backoff.

None of these is billed. Only a 2xx counts as a call; see Billing and usage.

Unknown parameters are refused

The API is strict about query parameters. A misspelt filter is refused with 400, never silently ignored:

400GET /v1/outages?stat=vic

{
  "error": {
    "code": "invalid_parameter",
    "message": "stat: is not a parameter of this endpoint",
    "param": "stat"
  }
}

That is deliberate. Ignored, ?stat=vic would quietly return every outage in the country — the worst way for a typo to fail on a metered API. The same goes for a value outside a parameter's vocabulary, such as status=open or a network id nobody issued.

Retrying

429 and 5xx are worth retrying, after a wait. Use retry-after for a 429 and an increasing backoff for a 5xx.
Every other 4xx describes the request. Retrying it unchanged returns the same error.
A failed upstream feed is not an error. If a network's feed is down, the API still answers 200 with the last data it recorded, and meta.data_as_of and the network's feed.status in GET/v1/networks say how fresh it is.