undici raises typed error objects so that failures can be distinguished\nprogrammatically. Every error class is exposed through the errors namespace of\nthe package:
import { errors } from 'undici'\n\nif (err instanceof errors.ConnectTimeoutError) {\n // handle connect timeout\n}\nAll errors, except HTTPParserError, extend UndiciError. Each error\ncarries a stable code string (for example UND_ERR_CONNECT_TIMEOUT) and a\nname.
Because the bundled (global) dispatcher may come from a different undici version\nthan the one you import directly, prefer matching on error.code rather than\ninstanceof errors.UndiciError:
if (err.code === 'UND_ERR_CONNECT_TIMEOUT') {\n // handle connect timeout\n}\n<Error>The base class for all undici errors. It is reliable with instanceof even when\nthe error originates from a different undici version, because the check is based\non a well-known symbol rather than the prototype chain.
<UndiciError>The socket was destroyed because establishing the connection exceeded the\nconnectTimeout option.
When autoSelectFamily is enabled and every attempted address times out, Node.js\nraises an AggregateError. undici normalizes these multi-address timeouts into a\nConnectTimeoutError so that the error shape is the same regardless of whether\nNode.js's per-address timer or undici's connectTimeout wins the race. The\noriginal AggregateError is preserved on error.cause.
<UndiciError>The socket was destroyed because receiving the response headers exceeded the\nheadersTimeout option.
<UndiciError>The socket was destroyed because the response headers exceeded the maximum\nallowed size.
\n" }, { "textRaw": "Class: `BodyTimeoutError`", "name": "BodyTimeoutError", "type": "class", "meta": { "added": [ "v1.0.0" ], "changes": [ { "version": "v7.16.0", "pr-url": "https://github.com/nodejs/undici/pull/4472", "description": "Made the error reliable with `instanceof`." } ] }, "desc": "<UndiciError>The socket was destroyed because reading the response body exceeded the\nbodyTimeout option.
<UndiciError>An invalid argument was passed to an undici API.
\n" }, { "textRaw": "Class: `InvalidReturnValueError`", "name": "InvalidReturnValueError", "type": "class", "meta": { "added": [ "v1.0.0" ], "changes": [ { "version": "v7.16.0", "pr-url": "https://github.com/nodejs/undici/pull/4472", "description": "Made the error reliable with `instanceof`." } ] }, "desc": "<UndiciError>A user-supplied callback or interceptor returned an invalid value.
\nname <string> Always 'InvalidReturnValueError'.code <string> Always 'UND_ERR_INVALID_RETURN_VALUE'.<UndiciError>The operation was aborted. This is the base class of RequestAbortedError.
<AbortError>The request was aborted by the user, typically through an AbortSignal.
<UndiciError>An expected error carrying a reason, used internally to surface a cause for a\nfailed or retried request (for example as the cause of another error).
<UndiciError>The length of the request body did not match the content-length header.
name <string> Always 'RequestContentLengthMismatchError'.code <string> Always 'UND_ERR_REQ_CONTENT_LENGTH_MISMATCH'.<UndiciError>The length of the response body did not match the content-length header.
name <string> Always 'ResponseContentLengthMismatchError'.code <string> Always 'UND_ERR_RES_CONTENT_LENGTH_MISMATCH'.<UndiciError>An operation was attempted on a client that has already been destroyed.
\n" }, { "textRaw": "Class: `ClientClosedError`", "name": "ClientClosedError", "type": "class", "meta": { "added": [ "v1.0.0" ], "changes": [ { "version": "v7.16.0", "pr-url": "https://github.com/nodejs/undici/pull/4472", "description": "Made the error reliable with `instanceof`." } ] }, "desc": "<UndiciError>An operation was attempted on a client that has already been closed.
\n" }, { "textRaw": "Class: `SocketError`", "name": "SocketError", "type": "class", "meta": { "added": [ "v1.0.0" ], "changes": [ { "version": "v7.16.0", "pr-url": "https://github.com/nodejs/undici/pull/4472", "description": "Made the error reliable with `instanceof`." } ] }, "desc": "<UndiciError>An error occurred on the underlying socket.
\nname <string> Always 'SocketError'.code <string> Always 'UND_ERR_SOCKET'.socket <SocketInfo> | <null> Metadata about the socket at the time of the error,\nor null when no socket information is available.The socket property, when present, holds the following fields:
interface SocketInfo {\n localAddress?: string\n localPort?: number\n remoteAddress?: string\n remotePort?: number\n remoteFamily?: string\n timeout?: number\n bytesWritten?: number\n bytesRead?: number\n}\n<UndiciError>Unsupported functionality was requested.
\n" }, { "textRaw": "Class: `BalancedPoolMissingUpstreamError`", "name": "BalancedPoolMissingUpstreamError", "type": "class", "meta": { "added": [ "v1.0.0" ], "changes": [ { "version": "v7.16.0", "pr-url": "https://github.com/nodejs/undici/pull/4472", "description": "Made the error reliable with `instanceof`." } ] }, "desc": "<UndiciError>No upstream has been added to the BalancedPool.
name <string> Always 'MissingUpstreamError'.code <string> Always 'UND_ERR_BPL_MISSING_UPSTREAM'.<Error>An error occurred while parsing the HTTP response. Unlike the other error\nclasses, HTTPParserError extends <Error> directly rather than UndiciError.
name <string> Always 'HTTPParserError'.code <string> An HPE_-prefixed parser error code, or undefined when no\ncode was provided.data <string> The raw data associated with the parser failure, or undefined when none was provided.<UndiciError>The response body exceeded the maximum allowed size.
\nname <string> Always 'ResponseExceededMaxSizeError'.code <string> Always 'UND_ERR_RES_EXCEEDED_MAX_SIZE'.<UndiciError>A request failed and could not be retried, for example because the body is\nstateful (a stream or AsyncIterable) and cannot be replayed.
name <string> Always 'RequestRetryError'.code <string> Always 'UND_ERR_REQ_RETRY'.statusCode <number> The HTTP status code of the failed response.data <Object> Retry metadata.\ncount <number> The number of retry attempts that were made.headers <Record><<string>, <string> | <string>[]> The response headers.<UndiciError>The response returned an error status code. This is raised, for example, when the\nthrowOnError option is enabled.
name <string> Always 'ResponseError'.code <string> Always 'UND_ERR_RESPONSE'.statusCode <number> The HTTP status code of the response.body <Object> | <string> | <null> The response body.headers <Object> | <string>[] | <null> The response headers.<UndiciError>A TLS connection to a proxy failed.
\nname <string> Always 'SecureProxyConnectionError'.code <string> Always 'UND_ERR_PRX_TLS'.cause <Error> The underlying error that caused the proxy connection to fail.<UndiciError>The maximum number of allowed origins has been reached.
\nname <string> Always 'MaxOriginsReachedError'.code <string> Always 'UND_ERR_MAX_ORIGINS_REACHED'.<UndiciError>An error occurred during SOCKS5 proxy negotiation.
\nname <string> Always 'Socks5ProxyError'.code <string> The error code. Default: 'UND_ERR_SOCKS5'.<UndiciError>A decompressed WebSocket message exceeded the maximum allowed size.
\n" } ] } ] }