Errors

Corti uses standard HTTP status codes. 4xx errors indicate a problem with the request; 5xx errors indicate a problem on Corti’s side. Error responses are in JSON and differ between the SDKs and the REST API. The tabs below cover each.

Some Corti products handle errors and authentication differently than what is described below:

Admin API — Separate from the Corti API used for speech to text, text generation, and agentic workflows. See the Administration API reference for details. Please contact us if you have interest in this functionality or further questions.
Agents API — The JSON format of the error response is different. See the Agents API docs for more info.
Embedded Assistant — Authentication is handled differently. See the Embedded Assistant Authentication docs for those methods.

JavaScript SDK
C# .NET SDK
REST API

The SDK throws typed error classes on any non-2xx response or internal failure. Each class exposes a different set of attributes. See Error Handling for full details.

Error Classes

Class	Thrown when	Attributes
`CortiError`	API returned a non-2xx HTTP response (4xx / 5xx)	`message`, `statusCode`, `body`, `rawResponse`
`CortiSDKError`	SDK infrastructure error (e.g. localStorage unavailable)	`message`, `code`, `cause`
`ParseError`	Input validation failed (e.g. missing PKCE verifier, invalid JWT)	`message`, `errors`
`JsonError`	Response body could not be parsed as JSON	`message`, `errors`

HTTP Status Codes (JavaScript SDK)

400 — Bad Request

Error code	When it occurs	How to resolve
`bad_request`	The request body or query parameters are malformed or missing required fields.	Double check the fields submitted to be sure of correct format and necessary fields.

401 — Unauthorized

Token endpoint errors are returned as JSON in the response body. Corti API errors are returned in the WWW-Authenticate response header with no body. The header is not accessible from the exception directly; use .WithRawResponse() on the request if you need it.

Error code	When it occurs	How to resolve
`invalid_client`	Client authentication failed. There is a problem with the client ID.	Verify your `client_id` is correct.
`unauthorized_client`	Client authentication failed. There is a problem with the client secret.	Verify your `client_secret` is correct.
`invalid_token`	The bearer token is invalid or has expired. Check the `WWW-Authenticate` header for `error_description`.	Re-authenticate to obtain a fresh token and retry the request.

403 — Forbidden

When it occurs	How to resolve
Accessing a resource (interaction, recording, transcript, document) that belongs to a different client.	Verify the resource ID was created by the authenticated client.

404 — Not Found

Error	When it occurs	How to resolve
`Invalid '{resource_name}' '{resource_id}'`	The requested resource does not exist.	Verify the ID and parent resource ID is correct and was created under the authenticated tenant.

Attempting to access a resource that belongs to a different OAuth client also returns a 404, not a 403. This is intentional. Returning a 403 would confirm that the resource exists, which is a security risk.

429 — Too Many Requests

You have exceeded the rate limit for the API. The SDK automatically retries with exponential backoff. The default retry limit is 2. Override per request:

const response = await client.interactions.create(..., {
    maxRetries: 0, // disable retries for this request
});

If the error persists, reduce request frequency or contact support to discuss your rate limit requirements.

500 — Internal Server Error

An unexpected error occurred on the Corti side. Double check the request format and retry the request. If the issue persists, contact support.

503 — Service Unavailable

The service is temporarily unavailable. Retry with exponential backoff. Monitor the status page.

WebSocket APIs (JavaScript SDK)

WebSocket errors from /streams and /transcribe are surfaced as plain Error objects whose message is the server status code (e.g. CONFIG_DENIED, CONFIG_MISSING, CONFIG_TIMEOUT).

Every CONFIG_* server message also carries a reason field with human-readable details behind the failure. Whether you can read it depends on the mode you connected in:

Default mode (client.stream.connect({ id, configuration }) / client.transcribe.connect({ configuration })): the SDK handles the handshake-phase and CONFIG_* messages internally. It rejects connect() with just the bare code. The reason is not exposed.
awaitConfiguration: false or manual mode: the raw message, including msg.reason, flows through socket.on('message', …).

CONFIG_DENIED

You sent a config message, but it’s invalid.

`reason` from server	Likely cause	Fix
`invalid language code: must be a valid BCP 47 language tag`	`transcription.primaryLanguage` is not a supported code.	Use a supported language code.
`invalid output locale: language should not be empty`	`mode.type: "facts"` without `mode.outputLocale`.	Add `outputLocale`.
`invalid output locale: invalid language code: must be a valid BCP 47 language tag`	`mode.type: "facts"` with invalid `mode.outputLocale` code.	Use a supported language code
`unknown mode`	`mode.type` is not `"transcription"` or `"facts"`.	Use one of the two supported values.
`invalid participants`	Participant `role` is empty, exceeds 100 characters or 10 words, or contains control characters; or `channel` is negative.	Use a non-empty role (≤100 chars, ≤10 words, no control chars) and a non-negative `channel`.
`invalid audio format: MIME type not allowed...`	`audioFormat` MIME type is not in the supported list.	Use a supported MIME type or omit the field.

CONFIG_MISSING

You sent a non-config frame before any valid config message arrived.

Only reachable when you opt out of the automatic handshake. Default mode sends config for you.

`reason` from server	Cause	Fix
`No valid configuration provided for interaction`	A non-config frame reached the server before a config message. Typically sendAudio() / sendFlush() / sendEnd() in manual mode, or a raw socket.send() queued before OPEN in awaitConfiguration: false.	Be sure to call sendConfiguration() immediately after waitForOpen(), or pass configuration to connect() and let the SDK handle the handshake.`

CONFIG_TIMEOUT

The 10-second handshake window elapsed without any config message arriving.

Only reachable in manual mode. The default handshake sends config well within the 10s budget.

`reason` from server	Cause	Fix
Manual mode: no configuration provided within 10s	Server’s 10s handshake timer expired.	Call `sendConfiguration()` immediately after `waitForOpen()`.

The SDK throws typed exceptions on any non-2xx response. Each exception extends CortiClientApiException, which exposes Message, StatusCode, and Body. See Error Handling for full details.

Exceptions

Exception class	Thrown when	Attributes
`CortiClientApiException`	Any non-2xx HTTP response	`Message`, `StatusCode`, `Body`

Each status code throws a typed subclass with a more specific Body. See the accordions below for details.

HTTP Status Codes (C# .NET SDK)

400 — Bad Request

Exception class	Error code	When it occurs	How to resolve
`BadRequestError`	`bad_request`	The request body or query parameters are malformed or missing required fields.	Double check the fields submitted to be sure of correct format and necessary fields.

401 — Unauthorized

Exception class	Error code	When it occurs	How to resolve
`UnauthorizedError`	`invalid_client`	Client authentication failed. There is a problem with the client ID.	Verify your `client_id` is correct.
`UnauthorizedError`	`unauthorized_client`	Client authentication failed. There is a problem with the client secret.	Verify your `client_secret` is correct.
`UnauthorizedError`	`invalid_token`	The bearer token is invalid or has expired.	Re-authenticate to obtain a fresh token and retry the request.

403 — Forbidden

Exception class	When it occurs	How to resolve
`ForbiddenError`	Accessing a resource (interaction, recording, transcript, document) that belongs to a different client.	Verify the resource ID was created by the authenticated client.

404 — Not Found

Exception class	Error code	When it occurs	How to resolve
`NotFoundError`	`Invalid '{resource_name}' '{resource_id}'`	The requested resource does not exist.	Verify the ID and parent resource ID is correct and was created under the authenticated tenant.

422 — Unprocessable Entity

Exception class	When it occurs	How to resolve
`UnprocessableEntityError`	Request validation failed.	Check `Body` for `Code`, `Description`, `HowToFix`, `Detail`, and `Cause` fields.

429 — Too Many Requests

Exception class	When it occurs	How to resolve
`CortiClientApiException`	Rate limit exceeded after retries exhausted (default: 2 retries with backoff).	Reduce request frequency or contact support to discuss your rate limit requirements.

500 — Internal Server Error

Exception class	When it occurs	How to resolve
`InternalServerError`	An unexpected error occurred on the Corti side. `Body` contains `Detail`, `Type`, `Status`, and `RequestId`.	Double check your request format and retry the request. If the issue persists, contact support.

502 — Bad Gateway

Exception class	When it occurs	How to resolve
`BadGatewayError`	A gateway error occurred. `Body` contains `Detail`, `Type`, `Status`, and `RequestId`.	Retry the request. If the issue persists, contact support.

503 — Service Unavailable

Exception class	When it occurs	How to resolve
`CortiClientApiException`	The service is temporarily unavailable.	Retry with exponential backoff. Monitor the status page.

504 — Gateway Timeout

Exception class	When it occurs	How to resolve
`GatewayTimeoutError`	The gateway timed out. `Body` contains `Detail`, `Type`, `Status`, and `RequestId`.	Retry the request. If the issue persists, contact support.

WebSocket APIs (C# .NET SDK)

WebSocket errors from /streams and /transcribe surface as exceptions thrown by ConnectAsync() (with Message set to the server status code, e.g. CONFIG_DENIED, CONFIG_MISSING, CONFIG_TIMEOUT) or as typed events on the socket.

Every CONFIG_* server message also carries a Reason field with human-readable details behind the failure. Whether you can read it depends on how you connect:

Default mode (stream.ConnectAsync(new StreamConfig { … }) / transcribe.ConnectAsync(new TranscribeConfig { … })): the SDK handles the handshake-phase and CONFIG_* messages internally. It throws from ConnectAsync() with just the bare code. The Reason is not exposed.
Manual mode (ConnectAsync() with no config): the raw message, including msg.Reason, flows through the StreamConfigStatusMessage / TranscribeConfigStatusMessage event. Subscribe before calling ConnectAsync() to catch handshake-phase events.

CONFIG_DENIED

You sent a config message, but it’s invalid.

`reason` from server	Likely cause	Fix
`invalid language code: must be a valid BCP 47 language tag`	`transcription.primaryLanguage` is not a syntactically valid BCP-47 tag (e.g. `"english"`, `"en_US"`, empty string).	Use a supported language code.
`invalid output locale: language should not be empty`	`mode.type: "facts"` without `mode.outputLocale` (or with an empty value).	Set `mode.outputLocale` to a valid BCP-47 code whenever `mode.type` is `facts`.
`invalid output locale: invalid language code: must be a valid BCP 47 language tag`	`mode.type: "facts"` with a syntactically invalid `mode.outputLocale`.	Use a supported language code for `outputLocale`.
`unknown mode`	`mode.type` is not `transcription` or `facts`.	Use one of the two supported values.
`invalid participants`	Participant `role` is empty, exceeds 100 characters or 10 words, or contains control characters; or `channel` is negative.	Use a non-empty role (≤100 chars, ≤10 words, no control chars) and a non-negative `channel`.
`invalid audio format: MIME type not allowed...`	`audioFormat` MIME type is not in the supported list.	Use a supported MIME type or omit the field.

CONFIG_MISSING

You sent a non-config frame before any valid config message arrived.

Only reachable in manual mode. Default mode sends config for you.

`Reason` from server	Cause	Fix
`No valid configuration provided for interaction`	A non-config frame reached the server before a config message. Typically a `Send(byte[], …)` audio call, or a `Send(StreamFlushMessage, …)` / `Send(StreamEndMessage, …)` call before any `Send(StreamConfigMessage, …)`.	Call `Send(new StreamConfigMessage { … }, …)` (or `TranscribeConfigMessage`) as the first frame after `ConnectAsync()` returns, or pass the config directly to `ConnectAsync(new StreamConfig { … })` and let the SDK handle the handshake.

CONFIG_TIMEOUT

The 10-second handshake window elapsed without any config message arriving.

Only reachable in manual mode. The default handshake sends config well within the 10s budget.

`Reason` from server	Cause	Fix
`no configuration provided within 10s`	Server’s 10s handshake timer expired without receiving a config message.	Call `Send(new StreamConfigMessage { … }, …)` (or `TranscribeConfigMessage`) immediately after `ConnectAsync()` returns, or pass the config directly to `ConnectAsync(new StreamConfig { … })` and let the SDK handle the handshake.

Resource and API errors (all endpoints except the OAuth token endpoint) return JSON with requestid, status, type, detail, and validationErrors fields:

{
  "requestid": "<string>",
  "status": 400,
  "type": "<string>",
  "detail": "<string>",
  "validationErrors": [
    {}
  ]
}

Authentication errors from the OAuth token endpoint return error and error_description fields:

{
  "error": "invalid_client",
  "error_description": "Client authentication failed."
}

HTTP Status Codes (REST API)

400 — Bad Request

Error code	When it occurs	How to resolve
`invalid_request`	The request is missing a required parameter or is otherwise malformed.	Ensure required fields (`grant_type`,`scope`) are present and correctly formatted.
`unsupported_grant_type`	The `grant_type` value is not recognised by the server.	This API requires a `grant_type` of `client_credentials`. Corti Assistant requires alternate methods for `grant_type`.
`invalid_scope`	The requested scope does not exist or is not permitted for this client.	Use a valid scope. This API requires `openid`.

401 — Unauthorized

Token endpoint errors are returned as JSON in the response body. Corti API errors are returned in the WWW-Authenticate response header with no body. Check the header directly if the response body is empty.

Error code	When it occurs	How to resolve
`invalid_client`	Client authentication failed. There is a problem with the client ID.	Verify your `client_id` is correct.
`unauthorized_client`	Client authentication failed. There is a problem with the client secret	Verify your `client_secret` is correct.
`invalid_token`	The bearer token is invalid or has expired. Check the `WWW-Authenticate` header for `error_description`.	Re-authenticate to obtain a fresh token and retry the request.

403 — Forbidden

When it occurs	How to resolve
Accessing a resource (interaction, recording, transcript, document) that belongs to a different client.	Verify the resource ID was created by the authenticated client.

404 — Not Found

Error	When it occurs	How to resolve
`Invalid '{resource_name}' '{resource_id}'`	The requested resource does not exist.	Verify the ID and parent resource ID is correct and was created under the authenticated tenant.
`'{resource_name}' not found`	The requested resource does not exist.	Verify the ID and parent resource ID is correct and was created under the authenticated tenant.

429 — Too Many Requests

You have exceeded the rate limit for the API. Retry the request after a delay, using exponential backoff. If the error persists, reduce request frequency or contact support to discuss your rate limit requirements.

500 — Internal Server Error

An unexpected error occurred on the Corti side. Double check your request format and retry the request. If the issue persists, contact support.

503 — Service Unavailable

The service is temporarily unavailable. Retry with exponential backoff. Monitor the status page.

WebSocket APIs (REST API)

WebSocket errors from /streams and /transcribe arrive as plain JSON messages on the socket: { type: "CONFIG_DENIED", reason: "…" }, { type: "CONFIG_MISSING", reason: "…" }, etc. Without an SDK in the middle, you see every server message verbatim, including the reason field on every CONFIG_* event.

The raw protocol is manual mode out of the box. There’s no SDK layer handling the handshake for you. You open the socket, send { type: "config", configuration: { … } } yourself, and listen for CONFIG_ACCEPTED before sending audio. See the Streams API reference for the full protocol.

The server does not close the socket on CONFIG_DENIED or CONFIG_MISSING. Both codes reject the input but keep the connection open. Each subsequent non-config frame triggers a fresh CONFIG_MISSING response, one per frame, until the client closes the socket. SDK consumers don’t see this because the SDK calls close() on rejection internally. Raw-protocol clients should close the socket themselves once they receive either rejection.

CONFIG_DENIED

You sent a config message, but it’s invalid.

`reason` from server	Likely cause	Fix
`invalid language code: must be a valid BCP 47 language tag`	`transcription.primaryLanguage` is not a syntactically valid BCP-47 tag (e.g. `"english"`, `"en_US"`, empty string).	Use a supported language code.
`invalid output locale: language should not be empty`	`mode.type: "facts"` without `mode.outputLocale` (or with an empty value).	Set `mode.outputLocale` to a valid BCP-47 code whenever `mode.type` is `facts`.
`invalid output locale: invalid language code: must be a valid BCP 47 language tag`	`mode.type: "facts"` with a syntactically invalid `mode.outputLocale`.	Use a supported language code for `outputLocale`.
`unknown mode`	`mode.type` is not `transcription` or `facts`.	Use one of the two supported values.
`invalid participants`	Participant `role` is empty, exceeds 100 characters or 10 words, or contains control characters; or `channel` is negative.	Use a non-empty role (≤100 chars, ≤10 words, no control chars) and a non-negative `channel`.
`invalid audio format: MIME type not allowed...`	`audioFormat` MIME type is not in the supported list.	Use a supported MIME type or omit the field.

CONFIG_MISSING

You sent a non-config frame before any valid config message arrived.

`reason` from server	Cause	Fix
`No valid configuration provided for interaction`	A non-config frame (binary audio, `{ type: "flush" }`, `{ type: "end" }`) reached the server before a `{ type: "config", configuration: { … } }` message.	Send the config message as the first frame after the WebSocket opens. Wait for `CONFIG_ACCEPTED` before sending any other frame.

CONFIG_TIMEOUT

The 10-second handshake window elapsed without any config message arriving.

`reason` from server	Cause	Fix
`no configuration provided within 10s`	Server’s 10s handshake timer expired without receiving a config message.	Send `{ type: "config", configuration: { … } }` immediately after the WebSocket opens.

Corti Models APIs

Agentic APIs

Web Socket APIs

REST APIs

Admin APIs

Agentic APIs v1 (deprecated)

Errors

Error Classes

HTTP Status Codes (JavaScript SDK)

WebSocket APIs (JavaScript SDK)

Exceptions

HTTP Status Codes (C# .NET SDK)

WebSocket APIs (C# .NET SDK)

HTTP Status Codes (REST API)

WebSocket APIs (REST API)

​Error Classes

​HTTP Status Codes (JavaScript SDK)

​WebSocket APIs (JavaScript SDK)

​Exceptions

​HTTP Status Codes (C# .NET SDK)

​WebSocket APIs (C# .NET SDK)

​HTTP Status Codes (REST API)

​WebSocket APIs (REST API)

Error Classes

HTTP Status Codes (JavaScript SDK)

WebSocket APIs (JavaScript SDK)

Exceptions

HTTP Status Codes (C# .NET SDK)

WebSocket APIs (C# .NET SDK)

HTTP Status Codes (REST API)

WebSocket APIs (REST API)