Error 401: what to do when grok-4.3 fails

A 401 means authentication failed: the request carries no API key, or the key is invalid, deleted or expired.

401 Unauthorized means the request carries no valid credential. The gateway could not identify the caller, so the request never reaches the upstream model. Checking the Authorization header and the key status is the only path forward.

grok-4.3 is served by xAI. Everything on this page — triggers, fixes and measured data — is compiled from the real runtime behaviour of this model at the gateway layer.

At this gateway, the most common trigger is: The Authorization header is missing. The recommended first action is: Send the header as Authorization: Bearer followed by your key.

Common causes

  • The Authorization header is missing
  • The key is misspelled or has stray whitespace
  • The key was deleted or disabled on the Tokens page
  • A key from another platform was used by mistake

How to fix

  • Send the header as Authorization: Bearer followed by your key
  • Generate a fresh key on the Tokens page
  • Check that you are not using a key from another service
  • Verify the key with a minimal curl request

Retry with exponential backoff

The snippet below retries when grok-4.3 returns 401, up to 5 attempts, with an increasing wait plus random jitter so concurrent calls do not retry in lockstep. Read the base URL and API key from environment variables — never hardcode them.

import os, time, random
import requests

BASE  = os.getenv("OPENAI_BASE_URL")   # e.g. https://<your-gateway>/v1
KEY   = os.getenv("OPENAI_API_KEY")
MODEL = 'grok-4.3'


def chat(messages, retries=5):
    """Retry with exponential backoff + jitter."""
    for i in range(retries):
        try:
            r = requests.post(
                BASE + "/chat/completions",
                headers={"Authorization": "Bearer " + KEY},
                json={"model": MODEL, "messages": messages, "stream": True},
                timeout=60,
            )
            if r.status_code == 429 or r.status_code >= 500:
                time.sleep(min(2 ** i + random.uniform(0, 1), 30))
                continue
            r.raise_for_status()
            return r.json()
        except requests.exceptions.Timeout:
            time.sleep(min(2 ** i + random.uniform(0, 1), 30))
    raise RuntimeError("gave up after " + str(retries) + " retries")


print(chat([{"role": "user", "content": "hello"}]))

Key facts for this model

API endpointhttps://api.airai.cc/v1
OpenAI-compatibleOpenAI-compatible
VendorxAI
Context1M
CapabilitiesReasoning, Tools, Files, Vision
API formatsopenai, openai-response, openai-response-compact, anthropic, gemini, openai-alpha-search
Billing formulap * 1.25 + cr * 0.2 + c * 2.5) : tier("200k_plus", p * 2.5 + cr * 0.4 + c * 5

FAQ

Is 401 on grok-4.3 related to request body size?

The request parameters must change; retrying alone will not help. This is a client-side configuration issue; nothing changes server-side. The capability tags are Reasoning, Tools, Files, Vision, and parameter ceilings follow from that capability set. The 1M context window sets the maximum input per request; anything beyond it is rejected outright. Fail fast on parameter errors instead of spending retries on them. Truncate or summarise long inputs — it noticeably reduces 401.

When grok-4.3 returns 401, which fields should I read in the response body?

If it only happens in production, it is usually an environment difference, not the model. This model is served by xAI, so upstream status follows the vendor’s own announcements. Reproduce it once in a staging environment with the same request body.

Do failed requests count against my rate limit quota?

No charge — only output actually produced counts toward usage. With billing p * 1.25 + cr * 0.2 + c * 2.5) : tier("200k_plus", p * 2.5 + cr * 0.4 + c * 5, the cost of long output comes mostly from output tokens. When estimating cost from p * 1.25 + cr * 0.2 + c * 2.5) : tier("200k_plus", p * 2.5 + cr * 0.4 + c * 5, include the retry budget.

Is 401 more likely with direct frontend calls or backend proxying?

Keep a fallback model ready as well. Building a fallback into the architecture is more reliable than patching errors one by one. This model from xAI has several upstream nodes the gateway can switch between. Keep a lighter fallback model ready so the main flow never breaks.

Other errors on this model

Other models with the same error

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Data updated: 2026-10-10 18:35

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