Aider-AI/aider · error · GitHubCopilotTokenError

Response missing 'token' field

Error message

Response missing 'token' field

What it means

The Copilot token endpoint responded 200 but its JSON body lacked a usable 'token' field (response_data.get('token') returned None/empty). aider raises GitHubCopilotTokenError('Response missing 'token' field'). It indicates an unexpected but successful response payload — the endpoint contract changed or returned an error object with 200 — rather than a credential problem.

Source

Thrown at aider/models.py:981

            }

            url = "https://api.github.com/copilot_internal/v2/token"
            res = requests.get(url, headers=headers)
            if res.status_code != 200:
                safe_headers = {k: v for k, v in headers.items() if k != "Authorization"}
                token_preview = github_token[:5] + "..." if len(github_token) >= 5 else github_token
                safe_headers["Authorization"] = f"Bearer {token_preview}"
                raise GitHubCopilotTokenError(
                    f"GitHub Copilot API request failed (Status: {res.status_code})\n"
                    f"URL: {url}\n"
                    f"Headers: {json.dumps(safe_headers, indent=2)}\n"
                    f"JSON: {res.text}"
                )

            response_data = res.json()
            token = response_data.get("token")
            if not token:
                raise GitHubCopilotTokenError("Response missing 'token' field")

            os.environ[openai_api_key] = token

    def send_completion(self, messages, functions, stream, temperature=None):
        if os.environ.get("AIDER_SANITY_CHECK_TURNS"):
            sanity_check_messages(messages)

        if self.is_deepseek_r1():
            messages = ensure_alternating_roles(messages)

        kwargs = dict(
            model=self.name,
            stream=stream,
        )

        if self.use_temperature is not False:
            if temperature is None:
                if isinstance(self.use_temperature, bool):

View on GitHub (pinned to 5dc9490bb3)

Solutions

1. Update aider to the latest release (pip install --upgrade aider-chat) — schema drift is patched upstream quickly.
2. Retry once; a transient/garbled response (proxy interference) can produce a body without 'token'.
3. If behind a corporate proxy, bypass it for api.github.com and retry.
4. Report upstream at the aider repo if the newest version still fails — include the (redacted) response shape.

try:
    out = model.send_completion(messages, None, False)
except Exception as e:
    if "Response missing 'token' field" in str(e):
        # schema drift or transient body: upgrade aider, retry once
        raise SystemExit("Copilot token response malformed — update aider-chat and retry.")
    raise

When it happens

Trigger: GitHub changing/reshaping the undocumented copilot_internal/v2/token response schema, or a proxy/interceptor returning a 200 JSON body without 'token'. Only occurs after a 200 status passed the status check, so auth already worked.

Common situations: GitHub-side API contract drift breaking older aider versions months after release; corporate TLS-inspecting proxies rewriting responses; extremely rare relative to 401/403 errors.

Related errors

• Bad/missing filename. The filename must be alone on the line
• Expected `=======`
• Expected `>>>>>>> REPLACE` or `=======`
• {processed}\n^^^ {err}
• Invalid patch line found in update section: {line}

AI-assisted analysis of Aider-AI/aider@5dc9490bb3 (2026-08-15). Data as JSON: /api/errors/dc99e22d8ca4a237. Report an issue: GitHub.