axios error.response is undefined on network-level failure

Direct answer

error.response is undefined because the request never produced an HTTP response. DNS failures, connection refused, timeouts, and aborts are transport-level rejections; Axios still rejects with an AxiosError, but leaves response unset. Reading error.response.status before confirming the object exists throws TypeError and blocks fallback logic.

Confirmed behavior

• When the server returns any HTTP response, including 4xx and 5xx, Axios populates error.response, so error.response.status is safe after confirming error.response exists.
• Network-level failures leave error.response undefined. error.code may carry Node-specific clues such as ENOTFOUND, ECONNREFUSED, ECONNABORTED, or ETIMEDOUT, but browser behavior is less standardized and error.request may be absent. Treat these as secondary hints, not a cross-platform guarantee.
• AbortController cancellation is a separate failure class. It may surface with a canceled or abort message, but the exact property depends on your Axios version and adapter, so confirm it in your runtime.

Response interceptor pattern

axios.interceptors.response.use(
  (response) => response,
  (error) => {
    if (!error.isAxiosError) {
      return Promise.reject(error);
    }

    if (error.response) {
      const status = error.response.status;
      // status-dependent logic runs only here
    } else {
      if (isCanceledError(error)) {
        return Promise.reject(new Error('Request canceled'));
      }
      // network-level failure: DNS, refused, timeout, etc.
    }

    return Promise.reject(error);
  }
);

function isCanceledError(error) {
  const message = String(error.message ?? '').toLowerCase();
  return message.includes('canceled') || message.includes('abort');
}

Prefer an explicit `if (error.response)` guard over optional chaining for branching. `error.response?.status` is safe for a single read, but an explicit guard makes the missing-response branch clearer in shared error handling.

Cancellation without CancelToken

Do not mix legacy CancelToken with AbortController. Pass `signal` from `new AbortController()` into the Axios request and call `controller.abort()` when needed. Check cancellation in the interceptor before any response-status logic.

Verification

• DNS failure or connection refused: expect error.response to be undefined.
• 500 response: expect error.response.status to be defined.
• Immediate AbortController abort: expect the cancellation branch, with no access to error.response.

Missing diagnostic detail: which Axios version and runtime are you targeting? Canceled-error detection changes by version, so this determines whether a message check or a version-specific property check is appropriate.