Error reference

The SDK’s own view of this is SDK errors (the HubError class, and adviseError). Three families of codes reach you, all in the same response envelope:

EIN, the hub’s own codes, always with HTTP 400;
EPX, the gateway’s refusals, with a real HTTP status (400, 401, 403, 404, 413, 429, 502, 503, 504);
EMC, the hub’s framework, which checks a request before the hub’s routes see it, with HTTP 400.

The blocks, and when to retry

EIN and EPX codes share the same numbering, so one rule reads both:

Block	Codes	Meaning	Client action
Terminal	`0001`–`0049`	the request can never succeed as sent	fix the input, the credential or the origin, or re-quote — never retry unchanged, and never re-quote once the user has sent the quote’s `executionTx`
Availability	`0050`–`0079`	retry later; never evidence about order state	back off and retry — except `EIN0050` with `error_params[0]` `"upstreamAuth"` (the hub sends it on `EIN0050` from any route that calls an upstream, except `POST /quote/preview`, which answers a bare `EIN0050`), which only an operator can clear. On a submission, an availability answer is a lost answer (Handling errors — a lost answer)
Busy	`0080`–`0099`	back off	wait `error_params[0]` milliseconds (`EIN0080`, and the gateway’s `EPX0080` and `EPX0082`, which also send `Retry-After` in seconds; `EPX0081` sends only `Retry-After`), then retry

The TypeScript SDK exposes the rule as HubError.retryable / retryAfterMs. What a retry means per block, and why EIN0052 and a post-forward EIN0050/EIN0081 on POST /order/openfor need more than a retry loop: Handling errors.

Hub codes (`EIN`)

Code	Name	Meaning	Reference / params	Action
`EIN0001`	invalid form	a request field or the body failed validation	the field (`amount`, `body`, …; `x-infinity-subject` for a subject missing where the hub requires one, or outside its rule); on an asset-reference chain mismatch, params `[reference chain, request chain]`	fix the input
`EIN0002`	unsupported corridor	an asset or corridor does not resolve	a detail	pick another asset or chain
`EIN0003`	invalid amount	defensive only — amount validation reports `EIN0001`
`EIN0004`	—	reserved, never emitted (an unknown quote is `EIN0010`)
`EIN0005`	quote expired	the quote or preparation is no longer submittable: past `expiresAt` (on a proxy-lane registration, past its 20-minute window), or its template is no longer held		re-quote and re-sign — normal flow before anything is sent. Never once the user’s transaction is out (a proxy-lane registration, `POST /order`): a new quote means a second transaction (Execution errors)
`EIN0006`	epoch superseded	the configuration the quote ran under changed		re-quote — except on `POST /order`, which comes after the user’s transaction: as `EIN0005`
`EIN0007`	rejected	the hub’s own fail-closed checks refused it (a Solana envelope, a template, a proxy-lane registration the aggregator refused, the `POST /order` re-approval, which every OIF-lane quote fails (known issue), a route whose service is not configured, …)	a detail; a proxy-lane registration refused after `expiresAt` reads `fail-closed rejected: upstream refused: http 400 (QUOTE_EXPIRED)`	re-quote; quote the `request_id` if it repeats — except after the user’s transaction is out (a proxy-lane registration, `POST /order`): as `EIN0005` (known issue)
`EIN0008`	no viable route	a fact about the corridor	`providerRefused` (another amount); `notFillable` + params `[dest chain]` (another destination); or empty	change the request
`EIN0009`	order not found	unknown id, or not yours (`GET /order/{orderId}/status` answers another organization’s order, or one placed under another subject, exactly as an unknown one); on `GET /onchain/{id}/order`, an Open not observed yet — or a non-EVM origin, which never gets a tuple (known issue)		check the id namespace; on `GET /onchain/{id}/order`, poll for an EVM-origin order only
`EIN0010`	bad signature	a missing or misplaced order signature, a bad one where the hub checks it (`POST /order`; the format on `aggregator-gasless`), or an unknown or foreign quote (one code on purpose). The hub does not verify an `oif-escrow-gasless` signature: a bad one comes back as `EIN0021`		send the signature the lane expects (none on a proxy lane) and re-post; re-quote only before the user’s transaction is out
`EIN0021`	order declined	the solver or provider refused a signed openFor order (any signed lane), a bad `oif-escrow-gasless` signature included; nothing was opened	the upstream status and code	re-quote. Don’t re-post the declined body: the repeat answers `EIN0050`, then `EIN0052` (known issue)
`EIN0049`	internal	scrubbed internal error		quote the `request_id`
`EIN0050`	upstream unavailable	quote/order upstream unavailable, or an upstream refused the hub’s own credential	on `POST /quote` and `/quote/prepare`, params `[cause]`: `responseRejected`, `solverUnavailable`, `providerMissed` or `upstreamAuth` (reference `quote: unavailable (<cause>)`); on `POST /order/openfor` and `GET /order/{orderId}/status`, params `[upstreamAuth]` (reference `upstreamAuth`) for the refused credential; `POST /quote/preview` answers every provider failure bare	retry later (not `upstreamAuth`: an operator must renew the credential)
`EIN0051`	service unavailable	a store or projection read was unavailable, or an on-chain answer the hub cannot date		retry later — never read it as “no fill”
`EIN0052`	outcome unknown	a submission of this quote may have opened the order: an earlier one went unanswered (a submission cut while the hub was forwarding it included — known issue), or this one was answered in a way the hub cannot read		never re-quote; re-posting is safe and answers `EIN0052` until an operator reconciles the submission
`EIN0080`	rate limited	the hub’s token bucket for your organization: the quote routes and the order routes each have one	params `[retryAfterMs]`: a suggested back-off, `floor(1000 / tenantRps)` ms and at least 1, on every route; reference `rate limit shed, retry after <n>ms` (informational — read the param)	wait, then retry
`EIN0081`	busy	admission shed: the in-flight quote cap, the upstream-status projection table, and on `POST /order/openfor` the forward-reservation table (store-less assemblies), the hub’s outbound limiter to the upstream, or the upstream’s own 429		back off (Submit order (openFor) for openFor)

Codes EIN0011 to EIN0020 belong to hub routes that are not part of the partner API.

Gateway codes (`EPX`)

The gateway checks every call before the hub sees it. It answers its own refusals in the hub’s envelope, with the real HTTP status and an EPX code in the same blocks as the hub’s codes: the body’s message and the entry’s error_message are the Message column below, there is no error_reference, and the X-Request-Id header names the call. EPX0080 and EPX0082 carry their back-off in error_params[0] (milliseconds) and in a Retry-After header (seconds); EPX0081 in Retry-After only.

Code	HTTP	Message	When	Action
`EPX0001`	401	Missing or malformed API key	no credential header at all, or an `x-api-key` that is not `c8n_sk_` followed by 43 base64url characters	copy the secret key again from the hub dashboard; a page sends `x-project-id` instead
`EPX0002`	401	Invalid API key	the key is unknown, revoked or expired	make a new key in the hub dashboard
`EPX0003`	404	Route not found	no such route or method under the version, or `GET /orders` with a project id (from a browser, its pre-flight is refused, so the page sees a CORS failure)	check the method and the path; read the order history from your server, with a secret key
`EPX0004`	404	Version not available	the hub behind the gateway does not serve that API version	check the path: `/v1/…`
`EPX0005`	413	Request body too large	the request body is over 64 KiB	send a smaller body
`EPX0006`	400	Unreadable request body	the request body could not be read	fix the request
`EPX0007`	400	Send one credential	both `x-project-id` and `x-api-key` were sent	send one credential
`EPX0008`	401	Malformed project id	`x-project-id` is not `c8n_pk_` followed by 22 base64url characters	copy the id from your project page in the hub dashboard
`EPX0009`	401	Invalid project id	the project id is unknown	copy the id from your project page in the hub dashboard
`EPX0010`	403	Origin not allowed	the page’s origin is not on the project’s list, or the request has no `Origin` while a list is set	add the origin to the project’s list in the hub dashboard; a server calls with a secret key
`EPX0050`	502	Hub unavailable	the hub is unreachable	retry later; on a submission, the answer is lost: look the order up before re-posting
`EPX0051`	503	Hub access unavailable	the gateway’s own access to the hub is unavailable	retry later; on a submission, as `EPX0050`
`EPX0052`	504	Hub timed out	the hub did not answer in time: 20 s on the three quote routes, 10 s on every other route	retry later; on a submission the outcome is unknown: as `EPX0050`
`EPX0053`	503	Key check unavailable	the gateway could not check the key or the project id; the call never reached the hub	retry later
`EPX0080`	429	Too many requests	a pool is spent: your organization’s, shared by all its secret keys, or your project id’s, shared by all its visitors	wait `error_params[0]` ms, then retry
`EPX0081`	429	Too many failed attempts	20 missing, malformed or unknown keys or project ids from this IP within a minute: every call from it, valid ones included, is refused for the rest of that minute	fix the credential and stop the caller that repeats it; wait `Retry-After` seconds (there are no `error_params`)
`EPX0082`	429	Too many requests from this client	this visitor IP’s own bucket, on project id calls	wait `error_params[0]` ms, then retry

A refused credential or origin (EPX0001, EPX0002, EPX0008–EPX0010) is in the terminal block, and only an operator can fix it: the SDK marks it HubError.isCredentialRefused, and adviseError routes it to your team, never to the user. Don’t retry it: refused credentials count toward EPX0081. The hub’s rate-limit rules and the gateway’s are side by side on API keys and rate limits.

Framework codes (`EMC`)

Returned by the hub’s framework before (or around) the hub’s own code. error_reference names the offending request field for the field codes.

Code	Meaning	When
`EMC0000`	internal server error	an unexpected crash
`EMC0005`	invalid request	a GET carrying a body with a JSON `Content-Type` (without one the body is not read); a POST with `Content-Type` exactly `application/json` and an empty body, or an over-limit body, which reads as empty; the hub’s per-IP limiter shedding a request (“DDoS check failed”, no `request_id` in the body). Always HTTP 400, so the SDK marks it not retryable, the per-IP limiter’s refusal included
`EMC0028`	invalid JSON	the body is not JSON
`EMC0029`	invalid content type	not `application/json` or `multipart/form-data`; reference `ContentType`, and the wire text is “invalid chars. in text”

The framework’s other codes concern what the gateway itself sends to the hub. If one ever reaches you, report it with its request_id.

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The blocks, and when to retry

Hub codes (`EIN`)

Gateway codes (`EPX`)

Framework codes (`EMC`)

See also

​The blocks, and when to retry

​Hub codes (EIN)

​Gateway codes (EPX)

​Framework codes (EMC)

​See also

The blocks, and when to retry

Hub codes (`EIN`)

Gateway codes (`EPX`)

Framework codes (`EMC`)

See also